Abstract: This study intended to provide some groundwork for the cultivating of M.maudiae var. rubicunda by studying the diurnal change of photosynthesis under different situation. Net photosynthetic rate (P_n), transpiration rate (T_r), stomatal uctance (G_s), concentration of CO₂ between cells (C_i), photosynthetic active radiation (PAR), relative humidity (RH) and atmospheric concentration of CO₂ (C_a) were tested and compared by Li-6400 portable photosynthesis system from August to September in 2016. The results indicated that M.maudiae var. rubicunda′s diurnal change of photosynthesis emerged diauxie curve with an obvious midday depression. T_r, C_i and G_s had largest influence on M.maudiae var. rubicunda′s diurnal change of photosynthesis while PAR, RH, C_a had the influence of secondary. The depression of Photosynthetic rate in August and September were mainly caused by Non-stomatal limitation. According to the study in contrast of August and September, hot weather had side effect on the photosynthesis of M.maudiae var. rubicunda, restraining the growth. In that case, the cultivating of M.maudiae var. rubicunda should be done in cool weather.