During the field campaign, after taking into account the randomness of the working platform, the measuring coordinate system of the mobile Doppler lidar may no longer be the ground reference frame, which will lead to difficulty for the three-dimensional vector wind field inversion. Three-dimensional space coordinate rotation transformation method is proposed to establish the general relation between the measurement coordinate system and the ground reference frame, and then a general formula for three-dimensional wind field inversion is derived. In addition, in the process of beam scanning, due to the restriction of two-dimensional scanner machining precision and other limitations, there is a certain orientation error of the laser beam. The wind field measurement errors caused by beam pointing deviation are studied quantitatively by using Monte-Carlo simulation method. The results show that when the horizontal wind speed is 100 m/s, the horizontal wind speed error is 0.712 m/s and wind direction error is 0.704° for 1° beam orientation error, which is consistent with the theoretical results. The results of theoretical analysis also show that when the horizontal wind speed is 100 m/s, the maximum deviations of horizontal wind speed and direction would be 1.16 m/s and 1° respectively for 1° maximum deviation of beam direction.