The impact of cubic phase plate decenter on the imaging of wavefront coding system is analyzed, and the phase component of pupil function of wavefront coding system with the tilt and decenter parameters is calculated. It presents that decenter can also enlarge or reduce the phase factor and the amount of defocus. The simulation indicates that the decenter makes the system modulation transfer function (MTF) drop through changing the energy distribution and the sagittal or meridional length of point spread function (PSF). It also indicates that the effect of z-direction decenter is lower than that of x-direction or y-direction decenter. The experimental results show that decenter has lower influence on PSF in a certain range, and the clarity of restored images has excellent consistency in the range of depth of focus, but extension of depth of focus drops with decenter. The experimental results confirm the analysis of decenter. This study has high application value in the space optical system, microscopy system, and infrared imaging system with the wavefront coding technology.