In this study, Zhuliangyou4024 and Jinyou402, two hybrid early rice combination and Hyou159 and Jinyou207, two late combination were employed for tested materials, the effects of different cultivation density(they were A1(13.3 cm×20 cm), A2(16.7 cm×20 cm), A3(20 cm×20 cm), A4(13.3 cm×26 cm)) on canopy apparent photosynthesis(CAP)and yield were studied. The results showed that the yield of early hybrid rice combination Zhuliangyou4024 and Jinyou402 was showed decreased from A2, A1, A3 to A4 in turn, which indicated that A2 was a suitable cultivation density for early rice of double cropping. The effective panicle number, grain number per panicle and yield of treatment A3 of late combination Hyou159 were the highest in two years. The effective panicle number and yield of treatment A4 of late combination Jinyou207 were the highest in two years, which indicated the suitable planting density of late rice were greatly affected by their tillering ability. The combination with strong tillering ability could adopt small transplanting density. High effective leaf area index, effective leaf area index, maximum leaf area index of two early hybrid rice combination Zhuliangyou4024 and Jinyou402 were increased with the density increased during the whole growth period. High effective leaf area index, effective leaf area index, maximum leaf area index of Hyou159 decreased from A3, A4, A2, to A1 in turn in the first 13 d of heading stage, which indicated that increasing planting density of early hybrid rice combination Zhuliangyou4024 could improve its leaf area index, and decreasing planting density of late combination Hyou159 could improve its leaf area index. The results of correlation analysis showed that high effective leaf area index, effective leaf area index, maximum leaf area index in full heading stage and mature period, effective leaf area index, maximum leaf area index, flag leaf photosynthetic rate after 13 d of heading stage had significant or very significant positive correlation with yield, which indicated that maintaining larger leaf area index and higher photosynthetic rate of flag leaf after heading stage were the key measures to acquire high yield of double cropping rice.