Scanning accuracy of phased-array laser radar is one of the significant features of liquid crystal phased-array component. One method is proposed to obtain the quantitative calculation of the scanning error. Rayleigh-Sommerfeld formula is utilized to figure out the far-field laser beam accurately and the angle errors is gained. Then the scanning error can be measured based on the ratio of angle error to 3 dB main-lobe width. Finally three typical factors which are voltage discreted, manufactural accuracy, and Gaussian pre-processing, are simulated using this method, and it can be concluded that the magnitudes of the scanning errors are on the orders of 10-3,10-2,10-5, respectively. Thereby, the impact of the manufactural accuracy on the scanning accuracy must be emphasized for laser radar liquid crystal phased-array component.