Samples of Lentinus edodes, a kind of mushroom, were exposed to insecticide chlorpyrifos to study the effects of washing methods on the removal of the residues. The results indicated that different washing ways led to 0.32%～100.00% removal of pesticide residues. In most cases, washing operations led to a gradual decrease in residue levels, particularly washing with detergents or running tap water. The results indicated that washing with detergents could remove 54.72%～56.69% of pesticide residues at level of 64.49 mg/kg . The chlorpyrifos at level of 0.39 mg·kg^-1 was completely removed after washing with running tap water, detergents or mild water (below LOD of 0.0016 mg·kg^-1). The effect of washing with running tap water was not good when initial residue of chlorpyrifos was more than 3.91 mg·kg^-1, but it was better with salt solution.