Abstract: The aim of the paper was to study the differences of the effects that the high temperature produces on the seed setting rate and grain weight and the relationship between the physiological and biochemical indexes, and also to find the best period to study the high-temperature resistance variety and high temperature sensitive variety. This paper utilized high temperature stress to treat the high temperature sensitive variety at different stages. The results indicated that in grain-filling and seed setting stages, the high-temperature resistance variety still maintained the higher level and the differences between varieties was significant. The increase of soluble sugar content of the high-temperature resistance variety (64%) exceeded the increase of soluble sugar content of the high-temperature sensitive variety (32% ). And the increase of soluble protein content of the high-temperature resistance variety was significant (Which had increased of 41%), while the high temperature sensitive variety reduced greatly (Which had reduced 16% ). The high temperature stress occurring on the grain-filling and seed setting stages could distinguish the high-temperature resistance variety and high temperature sensitive variety, and it also maintained a high lever of seed setting rate and seed weigh, so the grain-filling and seed setting stages were probably the best periods to research the high-temperature resistance variety and high temperature sensitive variety.