In order to study the feasibility of using nonlinear ultrasonic testing technology to evaluate the tensile strength of materials, nonlinear ultrasonic testing and mechanical tensile tests were carried out on 3D printing aluminum alloy materials with different forming angles. The results show that there is a strong correlation between the tensile strength, the microscopic defect ratio and the acoustic nonlinearity parameter of the material. With the increase of the microscopic defect ratio of the material, the acoustic nonlinearity parameter increases, while the tensile strength tends to decrease. Thus, the acoustic nonlinearity parameter can be used to evaluate the strength of the material. In addition, fatigue tests were carried out on 3D printing aluminum alloy specimens with different forming angles. The findings reveal that the acoustic nonlinearity parameter of the specimens after fatigue loading increases with the initiation of microcracks. Therefore, nonlinear ultrasonic testing technology can be used for mechanical performance evaluation and microcrack detection of 3D printing aluminum alloy materials.