Abstract: Effects of different harvest date on the quality of japonica rice were studied by detecting the odor,texture and microstructure of japonica rice. The results showed that the odor of japonica rice with different harvest date was significantly different(p<0.05). With the increase of hervest date,especially 54 days after tull heading,the hardness of japonica rice was lower,the elasticity increased,the adhesiveness was higher,the adhesive viscosity was low,and the eating quality of japonica rice was better. The study also found that with the increasing of harvest date,the radiation shape of the cross section of japonica rice was from unclear to clear then to fuzzy even disappeared. The surface of endosperm cells were from smooth and consisting of few pores,and the starch grains lines being not clear,to rough porous,and the starch grains lines being clear. The starch were from consisting of most of compound granules arranging loosely to consisting of most of compound granule starch arranging closely and then consisting of most of starch granules arranging loosely. This showed that the microstructure of japonica rice with different harvest date were closely related to the cooking quality of japonica rice. It provided a new data support for the determination of the best harvest date,which would be benetical to the optionization of rice quality.