Abstract: Through the design of double edged axial-notched tube (DEAT) specimen and fixture, the expression of C* integral of DEAT specimen was obtained based on the principles of energy equivalent and load separation. A test method for the creep crack growth rate of thin-walled tubes with axial cracks has been established. The creep crack growth tests of N18 zircaloy thin-walled tubes at different load levels at 350℃ are carried out by using DEAT specimens. The results show that the creep load will significantly affect the creep crack growth rate of N18 zircaloy; the creep crack growth can be divided into two stages: steady state expansion and rapid expansion; the creep crack growth rate (da/dt) and C* integral have a good power-law relationship, and it can be used to predict the creep crack growth behavior of N18 zircaloy.