Accurate characterization of high-power laser parameters, especially the near-field and far-field distributions, is crucial for inertial confinement fusion (ICF) experiments. In this manuscript, we propose a method for computationally reconstructing the complex amplitude of high-power laser beams using modified coherent modulation imaging (MCMI). This method has the advantage of being able to simultaneously calculate both the near-field (intensity and wavefront/phase) and far-field (focal spot) distributions using the reconstructed complex amplitude. More importantly, the focal spot distributions at different focal planes can also be calculated. To verify the feasibility, the complex amplitude optical field of the high-power pulsed laser was measured after static aberration calibration. Experimental results also indicate that the near-field wavefront resolution of this method is higher than that of the Hartmann measurement. Additionally, the far-field focal spot exhibits a higher dynamic range (176 dB) than that of traditional direct imaging (62 dB).