A Laser sensor was used to measure propeller phase during aero-engine power shaft load inflight test. The 1P load of the shaft was analyzed using measured propeller phase and the load state. That the propeller phase signal measured in flight test was legible and stable indicated the measurement was successful. The propeller phase is an important parameter in aero-engine power shaft 1P load analysis and he measurement method of propeller phase put forward in this paper is feasible.