Abstract: The effects of environmental on photosynthesis can be reflected through the changes of chlorophyll fluorescence, in agronomic measures, planting density and N application play more significant role on photosynthesis. In this test, two rice varieties with different panicle type (panicle weight type rice variety‘Longjing27’and panicle number type rice variety‘Longjing25’) were chosen as materials, four density treatments and four N application time treatments were set to research the effect of plant density and N application on photosynthetic indexes and chlorophyll fluorescence parameters of rice. The result showed that chlorophyll content, photosynthetic rate, photosynthetic function date of panicle weight type rice variety‘Longjing27’were higher than panicle number type rice variety‘Longjing25’. Appropriate density and postponing N application time had significant role in promoting photosynthetic characteristics of flag leaf. Panicle weight type rice variety‘Longjing27’in D2 (29.7 cm×13.2 cm) density treatment and panicle number type rice variety‘Longjing25’in D3 (33 cm×9.9 cm) density treatment, postponing N application time could significantly improve their yield.