The invention discloses a method for preparing compound polyoxyalkane alkylene polymethyl trisiloxane as a cyclic platinum catalyst. The method comprises the following steps: the cyclic platinum catalyst takes reactant of silica gel and silylamine containing sulfane base as a carrier of platinum; a cyclic solid-supported platinum catalyst is obtained through the reaction adsorption of platinum onthe carrier; by use of the solid-supported platinum catalyst, heptamethyl trisiloxane is synthesized with two or more than two species of polyoxyalkane vinyl ether so as to obtain the compound polyoxyalkane alkylene polymethyl trisiloxane, wherein the mass ratio of the heptamethyl trisiloxane to the polyoxyalkane vinyl ether is 1:1.0-4.0, and the amount of the catalyst is 500 ppm of the total amount of the reactant. The catalyst is solid and easy to recycle repeatedly without wasting noble metal. The compound polyoxyalkane alkylene polymethyl trisiloxane had good stability and improves comprehensive service performance.