The red leaf line ‘Yanhong’ and the yellow leaf line ‘Jinseqiutian’ are excellent horticultural varieties of red maple (Acer rubum L.). To reveal?the biochemical metabolic mechanism of the leaf color transition to yellow or red for red maple, the contents of chlorophyll, anthocyanin, carotenoid, soluble sugar and pH value in the leaves at 5 development stages in autumn were surveyed. Moreover, the anthocyanin composition in colored leaves was quantified. The content of chlorophyll was declined in different lines during the leaf color formation phase. Chlorophyll content in ‘Jinseqiutian’ reduced to 0.06 mg·g^-1 in the middle of November. There was no difference in the carotenoid content between the 2 lines in the same time points. The carotenoid content was decreased slightly, when the leaf turned color. During the five stages, the content of soluble sugar increased in the early autumn and then decreased slightly in both lines, peaked at the midst of leaf coloring period. The change of pH value in leaf was not significant. The analysis of spectrophotometric showed that the anthocyanins content in ‘Yanhong’ had a rise about 3 times, while that of the yellow group increased a little. The HPLC analysis result showed that cyanidin accounted for more than 95% of anthocyanins, with a little of delphinidin being quantified in both lines. And the cyanidin was detected in ‘Yanhong’ at a concentration of 2.6 times higher than that in ‘Jinseqiutian’ in the colored leaves. These results suggested that the degradation of chlorophyll and the synthesis of cyanidin were the two major determinants for