Adaptive optics is widely used for aberration correction. But in practical applications, closed-loop correction requires a longer time, and open-loop correction is affected by the hysteresis effect of deformable mirrors. In this research, we propose a wavefront correction method for pyramid wavefront detector based on the P-U-net. P-U-net establishes a model of the entire adaptive optical system through data training, and constructs a direct nonlinear mapping relationship between the pupil image of the corner cone wavefront detector and the control voltage of the deformable mirror. The control voltage of the deformable mirror can be calculated through the pupil image of the pyramid wavefront detector. The feasibility of this method is verified by using simulation adaptive system theory. It can complete aberration correction within 50 ms, and the correction accuracy can reach 0.1 μm. Compared with traditional closed-loop adaptive correction algorithms, it can complete aberration correction in a shorter time, achieve higher accuracy, and has good application prospects.