【Objective】The study aims to explore the effects of spraying potassium dihydrogen phosphate (KH₂PO₄) at different concentrations and periods on the leaf color of Quercus texana. The relationship between phosphorus and potassium nutrition and leaf color change is elucidated, thereby providing a theoretical basis and technical support for the landscape application of Q. texana in the Yangtze River Basin.【Method】Six-year-old seedlings of Q. texana were sprayed with different concentrations of potassium dihydrogen phosphate solution at different growth stages. The CIE L^*, a^* and b^* color space parameters of leaves were measured using a colorimeter, and the brightness difference (ΔL^*), red-green difference (Δa^*), and yellow-blue difference (Δb^*) were then calculated. Concurrently, the contents of chlorophyll, anthocyanin and soluble sugar were determined. Finally, the correlations between physiological indexes and leaf color was comprehensively analyzed.【Result】(1) The ΔL^* (brightness) increase was maximized by spraying 0.4% KH₂PO₄ on August 30, and the Δb^* (yellowness) increase was maximized by spraying 0.6% KH₂PO₄ on August 30, whereas the Δa^* (redness) enhancement was maximized by spraying 0.4% KH₂PO₄ on September 15.(2) As the growth period progressed, a decline in chlorophyll content was observed, accompanied by an increase in anthocyanin content and the anthocyanin/chlorophyll ratio (K value). The soluble sugar content initially increased and then decreased. (3) The researchers found signifficantly positively correlated between the b^* value and the L^* value (P<0.05), as well as a significant positive correlation between the a^* value and the anthocyanin content (P<0.05). In addition, a negative correlation was observed between anthocyanin and chlorophyll (P<0.05), and a significant positive correlation was observed between anthocyanin and soluble sugar content (P<0.01). (4)Principal component analysis (PCA) extracted two principal components, with a cumulative contribution rate of 79.8%, of which the first component (PC1) contributed 52.6%. The comprehensive evaluation, based on the membership function method, showed that the comprehensive effect of spraying 0.8% KH₂PO₄ on September 15 was the best (with the highest D value).【Conclusion】Through the correlation analysis of physiological indexes and leaf color parameters, it was determined that the optimum treatment scheme for significanlty improve the leaf color performance of Q. texana in autumn was through the application of 0.8% KH₂PO₄ on September 15.