Abstract: 【Objective】 The population of cotton aphid migrating from overwintering host to cotton field and the environmental conditions in the Yellow River Basin are important factors for the damage caused by this aphid. The paper aims to clarify the effect of sowing date on the aphid population dynamics and cotton yield. 【Methods】 Effects of the sowing date April 16, April 26 and May 6 on the aphid population dynamics and cotton yield parameters were studied in cotton field of southern Hebei Province. 【Results】 The results showed that the cotton emergence rate increased with the delay of sowing period, and the cotton emergence rates on April 26 and May 6 were significantly higher than that on April 16. There was an obvious peak of cotton aphids in spring occurrence and a rapid decrease of aphid quantity in the treatments of April 16 and April 26, while there was no obvious peak of Aphids in spring in the treatments of May 6. In terms of yield, cotton yield increased significantly from 3.94 kg (April 16) to 5.46 kg (May 6) with the delay of sowing period. 【Conclusion】 Postponing the sowing dates of cotton can play the role of protecting seedling, reducing early aphid damage and ensuring yield.