【Objective】 The interspecific hybridization between the slash pine (Pinus elliottii) and the Honduras Caribbean pine (P. caribaea var. hondurensis) has resulted in the F₁ generation of the hybrid known as P. elliottii × P. caribaea var. hondurensis which exhibits significant hybrid vigor in terms of growth traits such as tree height and diameter at breast height (DBH). To investigate whether the F₂ generation exhibit trait segregation and growth decline, this study conducts multi-generational genetic assessments to systematically evaluate the breeding potential of the P. elliottii × P. caribaea var. hondurensis in higher generations. The ultimate goal is to provide a theoretical basis for the fixation of hybrid vigor and the upgrading of seed orchards. 【Method】 A total of 28 full-sibling F₁ family lines of P. elliottii × P. caribaea var. hondurensis (EHF1), 42 half-sibling F₂ family lines (EHF2), and three family lines resulting from the cross between P. elliottii and P. elliottii × P. caribaea var. hondurensis (EEH) were selected from the Hongling Seed Orchard in Taishan City, Guangdong Province. Additionally, three varieties of Caribbean pine were planted as controls: the Honduras Caribbean pine (P. caribaea var. hondurensis, PCH), the Bahamian Caribbean pine (P. caribaea var. bahamensis, PCB), and the Cuban Caribbean pine (P. caribaea var. caribaea, PCC), along with the slash pine (PEE). In 2015, a randomized incomplete block design was employed for planting, with one to four plants per single-row plot, resulting in a total of 28 replicates, with an average of 36 plants per family line. At the age of seven years, measurements of tree height and DBH were taken, and individual tree volume was calculated. A linear model was utilized for multiple comparisons of growth rates, as well as for calculating genetic parameters such as family heritability and breeding values for the EHF2 family groups. 【Result】 The overall survival rate of the experimental forest was 74.03%, with survival rates for EHF1, EHF2, EEH families, and the controls being 79.97%, 70.53%, 87.07% and 68.79%, respectively. The tallest tree, the largest DBH, and the highest individual tree volume were all found in the EHF2 family group, measuring 12.4 m, 27.4 cm, and 36.56 × 10^-2 m³, respectively. This suggests the potential for a genetic additive effect in the F₂ generation of P. elliottii × P. caribaea var. hondurensis. The growth rates of the three types of P. elliottii × P. caribaea var. hondurensis were significantly higher than those of the control slash pine and caribbean pine (P < 0.05). A further comparison among the three types of P. elliottii × P. caribaea var. hondurensis revealed that EHF1 had greater tree height and DBH than EHF2 and EEH families, although the differences did not reach statistical significance (P > 0.05). However, the average individual tree volume of EHF1 families was significantly higher (P < 0.05) than that of EHF2 and EEH families, with EHF1’s family average individual tree volume exceeding that of EHF2 by 9.28%. The primary factor contributing to the smaller average individual tree volume of EHF2 family compared to EHF1 was the higher proportion of trees below 8.5 m in height, while the proportion of trees above 8.5 m was relatively low. The family heritability of tree height, DBH, and individual tree volume for EHF2 family ranged from 0.515 to 0.637. When selecting the top 20 family lines based on individual tree volume breeding values, a genetic gain of 9.81% was observed. 【Conclusion】 The F₁ and F₂ generations of P. elliottii × P. caribaea var. hondurensis exhibit stronger hybrid vigor compared to the parent species, slash pine and Caribbean pine. The average individual tree volume of the F₁ hybrid is significantly greater than that of the F₂ generation produced from the primary seed orchard of P. elliottii × P. caribaea var. hondurensis, indicating a certain degree of growth decline in the F₂ generation compared to the F₁ generation. However, by selecting high breeding value clones, it is possible to establish seed orchards of P. elliottii × P. caribaea var. hondurensis that can produce progeny with growth levels that meet or even exceed the average growth levels of the F₁ generation. As growth rate is a typical quantitative trait, the establishment of a high-generation breeding system can facilitate the aggregation of favorable genes, effectively enhancing genetic gain and solidifying hybrid vigor. The establishment of high-generation seed orchards of P. elliottii × P. caribaea var. hondurensis, which have undergone multiple generations of genetic improvement, is a scientifically sound strategy for achieving both enhanced genetic gain and the fixation of hybrid vigor.