The invention relates to the field of corrosion fatigue crack measuring, in particular to a corrosion fatigue crack propagation testing device which is suitable for the corrosion fatigue crack propagation rate and a threshold value of materials measured by a flexibility method. The problems that in the prior art, the special requirement of the loading direction of a fatigue testing machine exists during clamping and testing, or parameters of a flexibility formula are needed to be modified during clamping and timing, and a solution is prone to leaking are solved. The device comprises a loading and exerting system, a crack detecting system and a temperature controlling system. The corrosion fatigue crack propagation testing device is simple and convenient to operate, install and use, when a normal stand type fatigue testing machine is in use, a CT sample can be loaded in the solution, the solution is effectively prevented from leaking, the flexibility formula is not needed to be modified, and the device is suitable for testing of the corrosion fatigue crack propagation rate and the threshold value of the materials calculated by the flexibility method under the solution of the normal temperature and the high temperature. The temperature control of the device is accurate, the normal solution can be measured, the corrosion fatigue crack propagation rate and the threshold value of the materials can be measured under the solution of the high temperature, and the corrosion state of the sample is easy to observe in real time.