Abstract: This paper proposes that the errors in stagnation pressure measurement due torotation state behind a rotor should include perception errors in addition to the weighting error and dynamic response errors. The analysis and experimental data show that the stagnation pressure in wake may be higher than that in the main flow,so the weighting error may be positive. These two conclusions are contrary to the affimation of reference [1]. This paper also puts forward various approaches to minimize the errors due to the rotation state.