Abstract: 【 Objective 】 This project aims to study the effects of different varieties and sowing dates on cotton growth, yield and boll distribution under wheat cotton intercropping system with a view to providing basis for sowing date and variety selection.【 Method 】 In the field experiment, the split-plot design was applied, two early maturing cotton varieties (Jinke 707 and Lumian 2387) were used as the main plot, 4 sowing dates including May 10 (SD₁), May 20 (SD₂), May 30 (SD₃), June 10(SD₄) were the sub-plot, and the effects of different varieties and sowing dates on cotton growing period, leaf area index, dry matter accumulation, boll weight distribution within cotton plant were investigated.【 Result 】 (1)With the delay of sowing dates, the seedling stage kept stable, the squaring stage was shortened, the flowering stage and the boll opening stage was shortened first and then extended. Jinke 707 under SD₁, Lumian 2387 under SD₂ were beneficial to the transfer of vegetative organs to reproductive organs. (2) Varieties and sowing dates had significant interaction on cotton yield. Jinke 707 had the highest lint yield under SD₁, which was 1,873 kg/hm². The yield of Lumian 2387 under SD₂ was the highest (1,767 kg/hm²). (3) The average boll weight of Jinke 707 was the greatest in the upper and middle cotton plant of SD₁, while that of the lower part of SD₃ treatment was the largest. The boll weight of Lumian 2387 in the lower, middle and upper part of SD₂ treatment was higher than that of other treatments. The boll distribution proportion of the lower and middle part increased with the delay of sowing time, while that of the upper part decreased with the delay of sowing time.【 Conclusion 】 Under the wheat-cotton intercropping system in the Yellow River basin, too late sowing will lead to a serious decrease in yield. In order to achieve high yield of cotton, Jinke 707 is sui Table for sowing on May 10 and Lumian cotton 2387 on May 20.