Abstract: According to the method of rotating pinhole needle, the effect of pinhole size and measure dot number on measurement accuracy is analyzed, and the direct measurement model of laser beams is founded. As the aperture ratio of measured beam and pinhole is 1%, the relative error is less than 2%. As the measure dot number of every scanning line is 30, the relative error is less than 0.2% so that the calculation results of satisfying measurement precision are obtained, which can be employed for the effective measurement of power distribution of large power laser, particularly suitable for the direct measurement of laser beams.