The mechanism of angular error on measurement result is analysed. Then, the influence way of angular error on inversion results in two approaches, namely, weight coefficient and baseline are studied by simulation of six groups of unimodal particle size distribution system (82 nm, 104 nm, 350 nm, 431 nm, 816 nm and 865 nm) and three groups of bimodal particle size distribution system (137/601 nm, 242/750 nm and 470/895 nm) and measurement of 306/974 nm bimodal particle size distribution system with different angular error. The results show that the influence of angular error on inversion results is derived from the baseline factor and weight coefficient factor simultaneously. The influence of weight coefficient factor on peak error and performance error is much bigger than the baseline factor. There is one exception that for the unimodal narrow distribution of small particles, the influence of baseline factor on peak error is a little more than weight coefficient factor, but the influence of weight coefficient factor on performance error is bigger than baseline factor.