Abstract: Based on the experiments covered by six different colored polythene film which included red，green，yellow，purple，blue and transparent film as a control，authors investigated the effect of accumulated photo-thermal effectiveness of different colored plastic film on leaf area index，yields and fruit exterior quality of greenhouse sweet pepper（Capsium annuum Lcv SJ-13 and CX-9）in Nanjing area of Jiangsu province in 2009.The results showed that accumulated photo-thermal effectiveness under red film treatment was the highest for the two cultivars，which reached 118.9 and 112.5 after planting 120 days.The leaf area index of sweet pepper under red film treatment was the highest，while leaf area index under blue film treatment was the lowest.The yields of sweet pepper under red film treatment attained the maximum，while sweet pepper treated by purple film was the lowest;they were 9.8% and 13.4% higher than the control under red film treatment，37.2 % and 40.5 % lower than the control under purple film treatment respectively for the two cultivars.The shoulder diameter，length，single weight of fruit and per carp thickness was the highest under red film treatment Harvest index，dry mass of fruit per unit area of the two cultivars and intercepted accumulated photo thermal effectiveness were in a linear relationship.The last harvest index of SJ-13 under purple film treatment was the highest，while the last harvest index of CX-9 under red film treatment was higher than other treatments.The study demonstrated that red film treatment were favorable for sweet pepper fruit dry matter accumulation，promoting formation of fruit yields and improvement of exterior quality，while the purple and blue film had the significant inhibitory effect.

Key words: Accumulated photo-thermal effectiveness, Leaf area, Yield, Quality, Model