Abstract: In order to determine the appropriate sowing time of sesame, the effects of light and temperature factors on the main characters of sesame under different sowing times were studied. 3 sesame varieties and 11 sowing times were selected. The results showed that the light and temperature factors had significant influence on main characters of sesame under different sowing times. The sesame growth periods were longer under the sowing time before June and after August. The plant height, first capsule height and yield per plant first increased and then decreased, the yield of the third sowing time was the highest. The capsule pitch number, grain number per capsule and thousand seed weight showed a decreasing trend. The accumulated temperature from sowing stage to squaring stage had a significantly negative correlation with capsule number per plant, which showed a significantly positive correlation with the accumulated temperature from squaring stage to early flowering period. The accumulated temperature from early flowering period to bloom stage showed a negative correlation with capsule pitch number, grain number per capsule, plot yield and yield per plant. The accumulated temperature from bloom stage to final flowering stage showed an extremely and significantly positive correlation with the main characters. The accumulated temperature from final flowering stage to mature period showed a significantly negative correlation with plant height, first capsule height and thousand seed weight, and an extremely negative correlation with capsule number per plant. In consequence, the relevant characters could be the best when the sesame was sowing timely, the appropriate sowing time of sesame was from late May to the middle of July in Nanchang region.