AZ31 magnesium alloy is treated by laser shock processing (LSP) using high-energy pulse laser beams. The dry-sliding wear tests of untreated and treated samples by LSP are conducted on the UMT-2 sliding wear tester. LSP can improve the wear resistance of AZ31 magnesium alloy through analyzing the micrographs of samples′ worn surfaces and worn debris and energy dispersive spectra of worn debris. Under the same conditions, friction coefficients and mass loss of AZ31 magnesium alloy treated by LSP are both significantly lower than untreated samples and the debris are even finer, which indicates that LSP can improve the wear resistance of AZ31 magnesium alloy. Besides, the friction mechanism of AZ31 magnesium alloy treated by LSP turns from delaminate wear into abrasive wear.