Abstract: The axial static tensile test of T700 carbon fiber composite materials was carried out, and the nonlinear ultrasonic testing technology was used to study the change rule of the nonlinear coefficient and attenuation coefficient under different tensile forces. The results show that the nonlinear coefficient and attenuation coefficient increased to a certain extent with the increase of tensile force. Compared with attenuation coefficient, the change trend of nonlinear coefficient was more obvious, which showed that the nonlinear ultrasonic testing technology had strong applicability to the early mechanical properties test of carbon fiber composite materials.