Taking the ‘Super Olympic’ Begonia Semperflorens as material, at room temperature (25 ℃/15 ℃) under normal sunshine condition or low temperature (15 ℃/6 ℃) under the different photoperiods, we sprayed the plants with abscisic acid (ABA). The endogenous pigment content, hormone contents and enzyme activities were comparatively analyzed to discuss the effects of exogenous ABA on anthocyanin biosynthesis and its mechanism. The results showed: (1) at room temperature and normal sunshine condition, the leaves will get red obviously on the 3th days when applying ABA (5 and 10 μmol/L). The anthocyanin content and endogenous ABA content of pigment increased significantly, while the endogenous gibberellin (GA) content decreased significantly. The anthocyanin biosynthesis and trans portation also increased significantly. (2) Under the condition of low temperature, the anthocyanin accumulation was closely related to photoperiod and the anthocyanin accumulation was the largest in short day; The anthocyanin accumulation in sunshine condition also increased, but there was no significant difference between sunshine and long sunshine. (3) The addition of 10 μmol/L ABA treatment increased the content of H donor NADPH in DFR reduction under long day and sunshine condition. Under low temperature treatment, the activities of DFR and UFGT enzymes increased and then increased the anthocyanin content. In addition, exogenous ABA treatment could increase endogenous ABA content and decrease the content of endogenous GA in low temperature and different photoperiod treatments, which was consistent with the production of anthocyanin. The results showed that exogenous ABA can affect the synthesis of anthocyanins by regulating key enzyme in anthocyanin synthesis of flowers. The application of suitable concentration of ABA can promote the B. semperflorens leaf anthocyanin accumulation and can be used to control leaf coloring in actual production.