Preparation of foamed plastic includes: according to certain ratio, blending synthesized phenolic resin and polyether polyol and meanwhile adding a foamer, a catalyst, a foam homogenizer and water; fully stirring the components, regulating the temperature of the system to required foaming temperature; fully blending polyisocyanate, in certain ratio, with the system, pouring the mixture into a moldwith an opening, and meanwhile successively measuring cream time, drawing time and non-sticky time; after the foam is aged completely, measuring related performances.