To tackle the problem that the camera-based beam analyzer often gives the different results of the laser beam quality, we analyze the impact of the relevant parameters on the measurement error of the laser beam. The beam diameter is calculated by the ISO 11146 standard based on the Gaussian model with the noise level corresponding to the real one. According to the actual operation during testing, four parameters are analyzed, including the light intensity saturation, integral area ratio, signal to noise ratio and actual beam size. Compared with the prior works, we found the key trend of the camera parameters on the measurement error and the correlation between the parameters, which will be helpful to put forward more specific requirements on how to choose the camera and how to set the integration time and the calculation area.