[Objective] Carbon fiber reinforced plastic (CFRP) propeller has the advantages of light weight, high strength, low vibration, low noise, corrosion resistance and fatigue resistance. Accurately knowing the deformation and strain of CFRP propeller blades under hydrodynamic load is of great significance to the study of fluid-structure coupling characteristics and optimal design. [Method] It is proposed to embed the fiber Bragg grating (FBG) sensors in the CFRP propeller, and build the CFRP propeller underwater dynamic strain test system. Two types of test conditions are set: ①The velocity is 0, and the rotation speed increases from 50r/min to 400r/ min; ②The speed is 427r/min, and the velocity increases from 0.0 to 1.6m/s. The dynamic strain data of the CFRP propeller under the above conditions is obtained by the FBG sensors, and the data is analyzed in time domain and spectrum domain.[Results] The dynamic strain frequencies of each FBG sensor on the CFRP propeller are same and related to the rotation speed; the dynamic strain amplitude of each FBG sensor has no obvious relationship with the rotation speed or velocity, it depends on the position of the FBG sensor, which reflects the structural mechanics feature of the propeller.[Conclusion] The underwater online dynamic strain test of the CFRP propeller is realized, and the test results are reasonable and reliable. It provides an important empirical basis for the theoretical design and analysis of the CFRP propeller, and is of great significance to the study of its hydrodynamic performance.