The work aims to improve the uniformity of surface coverage and the strengthening efficiency of shot peening (SESP). The distribution characteristics of surface coverage in width direction of shot peening was analyzed in single path shot peening (SPSP) by image processing techniques and the distribution uniformity of surface coverage and SESP were investigated in multi paths shot peening (MPSP) by normal distribution function. In SPSP, surface coverage in width direction of shot peening approximated normal distribution. In MPSP, the surface coverage was significantly affected by the adjacent path spacing. The smaller the path spacing was, the more uniform the surface coverage distribution was. There was an approximate linear relationship between the two. SESP increased as the path spacing decreased when the uniformity of surface coverage changed from 0.91 ~ 0.99. Moreover, SESP was also influenced by the length of the peened component and the corresponding SESP for different path spacing got closer as the length reduced. The uniformity of surface coverage can be improved on the basis of ensuring the SESP by selecting the adjacent path spacing reasonably.