The invention provides a method for preparing a chromium-rich compound layer on the surface of nickel-base superalloy. The chromium-rich compound layer is used for improving the surface hardness and high-temperature oxidization resistance of the nickel-base superalloy. The nickel-base superalloy is adopted as a cathode, stainless steel is adopted as an anode, and pulse direct-current voltage is applied between the two electrodes at room temperature. The voltage ranges from 300 V to 400 V, the duty ratio ranges from 20% to 50%, and electrolyte is prepared from, by mass, 45% to 80% of glycerinum, 5% to 20% of ethanediol, 5% to 20% of sodium bicarbonate and 5% to 20% of deionized water. The method is simple in procedure and low in cost, and the hardness of the prepared chromium-rich compoundlayer can reach 1000 HV or above, and is about three times that of an alloy matrix. The oxidation increase speed constant of the chromium-rich compound layer in air at the temperature of 900 DEG C ranges from 2.27*10<-2> g/m<2> h to 3.15*10<-2> g/m<2> h, and is only 1/3 to 1/2 of the matrix.