Abstract: Through a long-term located experiment，the effect of climatic elements on the grain number per spike of winter wheat were studied ．The results show that the days from the time when the average temperature of 5 days iS first heyond 4℃ to the time when the differentiation of stamen and pistil primordium begins are the main element to affect the grain num berper spikeof winterwheat．Anditis also afected by the lowest average temperature to the booting stage and the sunshine time to the heading stage．The influencing order of every factors to the grain number per spike of winter wheatisthe day num ber> sunshine time> the lowest average tem pe rature．So the relationships among the spike．the grain number and the 1000-grain weight should be cooperated to get high yield in different years．