The invention relates to a cleaning composition and a preparation method thereof, belonging to the technical field of cosmetics. The composition comprises, by weight, 15 to 50% of an amino acid surfactant, 10 to 30% of sodium alpha-olefinsulfonate and 15 to 50% of a betaine surfactant. The composition provided by the invention effectively overcomes the problem of difficulty in thickening of conventional products with the amino acid surfactant as a main surfactant, realizes thickening mainly through complex formulation of an anionic surfactant and an ampholytic surfactant, and constructs a micelle from sodium C14-16 olefin sulfonate and the betaine surfactant in a proper ratio so as to realize system thickening; other thickening agent is not needed; cold preparation can be realized, so production time is substantially reduced; and the prepared cleaning composition has abundant and fine foam, is greatly saved in cost and overcomes the problem of difficulty in thickening of the amino acidsurfactant and the problem of low foam of the amino acid surfactant.