Extension innovation method and TRIZ theory are both influential innovation method systems. In this paper, the relationship between TRIZ theory and the solution process of extension innovation method and the main tools is analyzed. It is found that there is a correlation between TRIZ solution tool and extension innovation method. TRIZ tool can be formally described by extension method. Some examples are given. It is concluded that these two innovative methods are closely related. Extension can be used as the theoretical basis of TRIZ. They should learn from each other, integrate with each other to improve the efficiency of solving innovation problems.