Based on the femtosecond pulse synchronously pumped optical parametric oscillator (SPOPO), we can generate the time-domain multi-mode nonclassical light field. and combine it with the space Hermite-Gaussian multi-mode, we can develop the spatio-temporal multi-model nonclassical light field, which is expected to further expand the quantum channel capacity and carry out the quantum measurement. We proposed an experimental scheme for compensation of astigmatism, realizing simultaneous resonance of HG01 and HG10 mode in the SPOPO. However, in the experiment it is found that the non-plane cavity will cause the image rotation of the output beam, thus bringing uncertainty to the experimental system. In this paper, we use the method of constructing the novel coordinate system of Gaussian beam to analyze the cause of coordinate rotation in a nonplane annular cavity. Furthermore, the multi-beam interference method is used to calculate the total rotation Angle of 25.641irc when the beam rotates 3.26, in the resonant cavity. The correctness of the theoretical calculation is verified by experimental simulation, then we analyze the rotation angles of the output mode of the cavity mirror under different coordinate rotationangles and different transmittance lenses. At last, we obtain the relationship between the rotation angles of the output mode and the two obtained. It provides a basis for further optimization of SPOPO system and research of multi-mode entanglement in Non-plane SPOPO.