The invention provides a preparation method used for a corrugated paper desk, comprising the steps as follows: a fixed stiffener which is convex out of the end surface is cut by the top end of a main supporting frame which is used for supporting the desktop; a concave trough is cut below the desktop; the fixed stiffener of the main supporting frame is closely embedded into the concave trough which is arranged below the desktop. A vertical through hole is cut on the main supporting frame; a vertical baffle is inserted into the vertical through hole; a horizontal through hole is cut on the main supporting frame; a horizontal screen is inserted into the horizontal through hole. Soft material is used for carrying out the tipping disposal of the edges and corners of the desktop; the bottom end of the main supporting frame which is contacted with the ground surface is added by plastic tipping, desktop and visible side edge craft liner tipping of all plates or plastic sealing rubber strip tipping. The desktop and two surfaces of all plates use mounted or plated waterproof material where fire retardant is dipped. The preparation method of the invention has simple and firm structure, light weight and excellent safety performance, and is not easy to harm people; meanwhile, the corrugate paper desk prepared by the preparation method has waterproof, fireproof and fire retarding performance, therefore, the service life of the seat can be prolonged, and the corrugated paper desk is especially suitable for children.