A method for removing pests from harvested vegetables has steps of extracting a first portion of harvested vegetables to obtain a vegetable cleanser, and cleaning a second portion of harvested vegetables with the vegetable cleanser, such that pests residing on the second portion of harvested vegetables are removed from the second portion of harvested vegetables, wherein the first portion of harvested vegetables and the second portion of harvested vegetables independently contain vegetables selected from the group consisting of vegetables belonging to the families of Cruciferae, Compositae, Chenopodiaceae and Amaranthaceae. The aforementioned method is effective at removing pests from harvested vegetables and satisfies urgent needs to reduce use of chemical pesticides.