Abstract: The effect of temperature increment before the over-wintering period on winter wheat development and grain yield was evaluated in an artificial climate chamber (TPG 1260, Australia) from 2010 to 2011. Winter wheat cultivar ‘Zhengmai 7698’ was used in this study. Three temperature increment treatments were involved in this study, i.e., temperature increment last 40, 50 and 60 days, respectively, before the over-wintering period. Control was not treated by temperature increment. The results showed that temperature increment before the over-wintering period had no significant effect on earlier phase spike differentiation. But an apparent effect on later phase spike differentiation was observed. High temperature effect on spike differentiation disappeared when the difference of effective accumulated temperature between the temperature increment treatment and the control was lower than 25 ℃. However, the foliar age at the jointing stage was enhanced more than 0.8, heading and physiological ripening were advanced 1 day each, when the effective accumulated temperature before the over-wintering period increased 60 ℃. Higher effective accumulated temperature before the over-wintering period accelerated winter wheat growth and development, which resulted in a short spike differentiation period. Winter wheat was easy to suffer freeze damage, which lead to floret abortion and spikelet death in spring under this situation. Meanwhile, higher effective accumulated temperature before the over-wintering period also reduced photosynthetic capacity of flag leaf, shortened the grain filling period, and led to wheat grain yield reduction.