Abstract: During 2000-2004，field experiments were conducted in Suzhou,Yumen,Jiayuguan of Jiuquan district to determine the effect of physiology and the heredity factor，the density，the temperature on male parent sterilemale flower of small melon for naked pumpkin. The result showed that small melon male parent flower of naked kernel pumpkin flowering normally after experienced 4-9 day for sterilemale flower，which is its physiology hereditary feature. Density has effect on the degree of sterilemale flower for small melon male parent，the higher the density was，the longer the sterilemale flower was and the more the invalid male flower of individual plant. The sterilemale flower experienced 11d under the 25cm×90cm density，and more 1d and 2d than 35cm×90cm and 40cm×90cm respectively. Average sterilemale flower of individual plant was 8.7 under the 25cm plant spacing，more 1.3 and 2.2 than 35cm and 40cm. It is the optimum density under the 40cm×90cm. From the sow seeds to the valid male flowering, the higher the temperature was，the shorter the invalid male flowering. Under the lower temperature, sterilemale flower quantity of individual plant was increased, and the time of sterilemale flowering was prolonged. The male parent sterilemale flower of small melon for naked kernel pumpkin was influenced by physiological and genetic background，density and temperature before male flowering.