Abstract: This paper investigates the influence of solution temperature on the microstructure and phase content of Ti6321 sheet materials by performing solid solution treatments of Ti6321 sheet and conducting microhardness test on the resulting microstructure. The relationship between microstructure and microhardness was analyzed. The results show that,with the increase of solid solution temperature,the microstructure of Ti6321 titanium alloy hot-rolled sheet undergoes a transformation from equiaxed microstructure to duplex microstructure,and then to Widmanstatten microstructure,and the content of primary α phase decreases significantly. The average micro Vickers hardness of the original Ti6321 titanium alloy hot-rolled sheet was 317.2 HV. As the solid solution temperature increases,the micro-Vickers hardness first increases,then remains unchanged,reaching a maximum value of 338.6 HV at a solution temperature of 900℃.