The invention relates to a temperature resistant water-base fracturing fluid thickening agent and a method for preparing the same. The thickening agent consists of acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid, N-vinyl pyrrolidone, complexing agent EDTA, chain transfer agent, sodium hydroxide aqueous solution and deionized water. The thickening agent is prepared by copolymerizing industrial raw materials of the acrylamide, the 2-acrylamido-2-methyl-1-propane sulfonic acid and the N-vinyl pyrrolidone in a reactor provided with a stirrer and a thermometer. The preparation method is simple. The prepared temperature resistant water-base fracturing fluid thickening agent does not contain insoluble residues, and the thickening agent of which the mass percentage is 0.5 percent is cut continuously for 30 minutes under the condition of 170S<-1> and 95 DEG C so that the viscosity is kept over 65 percent.