In the inertial confinement fusion high power laser systems, the severe low frequency wavefront distortion will result in laser beam cutoff, and reduce laser beam quality due to the pinhole of the spatial filter. Based on the spherical wave factor with phase ripples, the defocusing tolerance of spatial filtering has been studied in detail. In this model, the calculation result shows that the shift distance of the actual frequency-plane in the spatial filter is in inverse proportion to the curvature radius. In addition, the beam quality will reduce with the curvature radius decreasing. For a specified spatial filter with parfocal length of 11.8 m and filtering pinhole radius of 200 μrad, the curvature radius absolute value of the spherical wave factor should not be small than 3.5 km for the critical frequency. When the curvature radius grows to 3 km, the beam quality will deteriorate rapidly as the spatial frequency of phase ripples become smaller than 1.57 mm-1.