<i>[Background] </i>Wheat is the most important food crop, with the largest planting area in the world. However, in the production process, due to the species degradation and the occurrence of new diseases, the antigens of old varieties are lost, resulting in reduced yield and even no harvest. In order to ensure the stable yield and increase of wheat, the varieties need to be updated in time. By using different seasons and different places to carry out additional generation breeding of wheat, two or even three generations can be bred in a year. Accelerate wheat breeding process and accelerate the rate of variety renewal. <i>[Objective] </i>Kunming is an ideal place for wheat summer breeding in China due to its special climate. The optimal sowing time of wheat summer sowing in Kunming was studied to provide guidance for wheat planting of double seasons.<i> [Methods] </i>Local spring varieties were used as research materials, yield components of wheat were investigated and analyzed at four sowing dates. <i>[Results] </i>Agronomic traits data of summer sown wheat were lower than that of winter sown whea except nonbearing tillering numbert. The yield was the highest sowing on June 5. The reproductive coefficient, number of effective tillers, plant height, spike length, number of grains per spike, 100 ear grain weight and biomass decreased with the delay of sowing date. [Conclusion] Wheat summer sowing in Kunming should be no later than June 25 to obtain more breeding seeds.