【Objective】This study aims to explore the changes in leaf pigment content and color response of different genetic materials over various periods and to analyze the key factors influencing leaf coloration in five families of Triadica cochinchinensis from physiological and tissue structural perspectives. The findings are expected to provide a theoretical basis for selecting superior landscape varieties of T. cochinchinensis.【Method】 Five families of T. cochinchinensis with a height of 50 cm were selected as research materials. The leaf color changes of six time points (S1. 2021-10-29; S2. 2021-11-05; S3.2021-11-12; S4. 2021-11-19; S5. 2021-11-26; S6: 2021-12-03) were observed under natural conditions. Leaf color parameters (L^*, a^*, b^*), pigment content (chlorophyll, carotene, anthocyanin), and anatomical structure (upper and lower epidermis, palisade tissue, spongy tissue) were measured regularly. The dynamic changes in leaf color and genealogy selection of T. cochinchinensis were analyzed.【Result】(1)The leaf color of each T. cochinchinensis genealogy during the S1—S6 period primarily transitioned from light green to dark brownish yellow, then to reddish brown, and finally to bright red, with the ornamental period concentrated in the S5—S6 period. Among them, the SD8 family exhibited the highest ornamental value, with a color-changing period from the onset of discoloration (S2) to complete defoliation lasting 37 days.(2)The leaf color parameter a^* value of each family showed a linear upward trend, while the L^* and b^* values exhibited different change patterns. Specifically, greener leaves corresponded to lower a^* values, whereas redder leaves corresponded to higher a^* values, making a^* a representative parameter for the reddish leaf color of the five families.(3)Throughout the entire cycle, the chlorophyll and carotenoid contents of all T. cochinchinensis families decreased, while anthocyanin content increased, reaching a maximum at S3. The change from green to red leaves was mainly due to the proportionate distribution of pigment content. Before S3, chlorophyll content dominated the green leaf stage, and after S3, anthocyanin content dominated the red leaf stage.(4)During the color change from green to red, leaf thickness measurements indicated that pre-color change thickness was greater than post-color change thickness. The SD4 family experienced a significant 29.17% decrease in leaf thickness compared to other families (P<0.05). The upper epidermis thickness was greater than the lower epidermis across all families. Before the color change, the upper epidermis thickness of the SD6 family was significantly smaller than that of other families (P<0.05). Post-color change, the combined upper and lower epidermis thickness of the SD6 family accounted for the largest proportion among all families, significantly differing from others (P<0.05). Spongy tissue thickness exceeded palisade tissue thickness. The SD4 and SD6 families exhibited the most significant changes in spongy tissue thickness before and after the color change, at 30.59% and 0.87%, respectively. Palisade tissue thickness in the SD8 family significantly differed from other families (P<0.05), with a maximum change range of 29.92%.(5)Post-veraison, the leaf tissue structure of most T. cochinchinensis families showed that decreased leaf thickness, palisade tissue, and spongy tissue thickness facilitated anthocyanin accumulation, turning leaves red. No obvious variation attachments, such as particles or wax, were observed in leaf tissue, and no large air chambers appeared.【Conclusion】Leaf color change in T. cochinchinensis is primarily influenced by pigment dynamics, with anthocyanins being the main factor causing leaf reddening. Among the five families studied, the SD8 family demonstrated the most outstanding leaf color change and high ornamental value, making it particularly suitable for landscape greening. This study provides robust theoretical support for selecting T. cochinchinensis varieties and evaluating their ornamental value.