The invention provides a method for preparing an electron-doped high-temperature superconductor La2-xCexCuO4 film. Direct current magnetron sputtering equipment is used, and the invention comprises the following steps: firstly, according to La2-xCexCuO4 and the compounding ratio that 0.08 is less than or equal to x and x is less than or equal to 0.16, a solid phase reaction method is adopted to prepare a La2-xCexCuO4 ceramic target, and then the ceramic target is arranged on the target seat of a reaction chamber; secondly, substrate choice: SrTiO3, MgO or LaAlO3 is chosen, washed to be clean and then put on a heating stage in the reaction chamber, and the reaction chamber is closed; thirdly, the reaction chamber is vacuumized till the vacuum of a back side is superior to 2.0*10<-4>Pa; fourthly, the substrate is heated to 600-800 DEG C; fifthly, a reacting gas is charged in the reaction chamber; sixthly, the surface of the La2-xCexCuO4 ceramic target is pre-sputtered; seventhly, the heating stage is moved to the target position, and the La2-xCexCuO4 film begins to be prepared on the substrate; eighthly, after the reaction is ended, the reacting gas is stopped to be charged, the vacuum is pumped till the vacuum degree is superior to 2*10<-4> Pa, then the temperature of the substrate with La2-xCexCuO4 film prepared is dropped to the annealing temperature, and the annealing is performed; ninthly, the substrate with La2-xCexCuO4 film prepared is naturally cooled to the room temperature.