Solution and aging treatments are important approaches to improve mechanical properties and microstructure of aluminum-base alloys. In this research, a new type high strength Al-Cu-Si-Mn cast alloy was prepared. The effect of different solution and aging treatment temperatures on microstructure and mechanical properties of the Al-Cu-Si-Mn cast alloy were studied by means of microstructure observation and mechanical properties testing. Results showed that after solution treated at different temperatures for 12 h and aged at 175 ℃ for 12 h, with the increase of the solution temperature, both the tensile strength and the elongation of the alloy firstly increase and then decrease, and reach their peak values at 530 ℃. When the solution temperature is below 530 ℃, the microstructure of the alloy consists of α phase, undissolved θ phase and T phase; while when it exceeds 530 ℃, the microstructure only consists of α phase and T phase. After solution treated at 530 ℃ for 12 h and aged at different temperatures for 12 h, both the tensile strength and the elongation of the alloy firstly increase and then decrease with the increasing of temperature, and reach their peak values at 175 ℃. Therefore, the optimal heat treatment process for the alloy in this study is 12 h solution at 530 ℃ and 12 h aging at 175 ℃, and the corresponding tensile strength is 417 MPa, elongation is 4.0%. Solution and aging treatments are important approaches to improve mechanical properties and microstructure of aluminum-base alloys. In this research, a new type high strength Al-Cu-Si-Mn cast alloy was prepared. The effect of different solution and aging treatment temperatures on microstructure and mechanical properties of the Al-Cu-Si-Mn cast alloy were studied by means of microstructure observation and mechanical properties testing. Results showed that after solution treated at different temperatures for 12 h and aged at 175 ° C for 12 h, with the increase of the solution temperature, both the tensile strength and the elongation of the alloy first increase and then decrease, and reach their peak values ​​at 530 ° C. When the solution temperature is below 530 ° C., the microstructure of the alloy consists of α phase, undissolved θ phase and T phase; while when it exceeds 530 ° C, the microstructure only consists of α phase and T phase. After solution treated at 530 ° C for 12 h and aged at different temperatures for 12 h, both the tensile strength and the elongation of the alloy first increase and then decrease with the increasing temperature, and reach their peak values ​​at 175 ° C. Thus, the optimal heat treatment process for the alloy in this The study was 12 h solution at 530 ℃ and 12 h aging at 175 ℃, and the corresponding tensile strength was 417 MPa, elongation was 4.0%.