The invention provides a Bi(1-x)RExFe0.96Co0.02Mn0.02O3 ferroelectric film and a preparation method thereof. The preparation method comprises the following steps: preparing a Bi(1-x)RExFe0.96Co0.02Mn0.02O3 precursor solution from bismuth nitrate, ferric nitrate, cobalt nitrate, manganese acetate and nitric acid RE which serve as raw materials, wherein x is 0.06-0.12, and RE is La, Eu or Er; and coating the precursor solution on a substrate in a spinning manner, uniformly coating, baking and annealing to obtain the Bi(1-x)RExFe0.96Co0.02Mn0.02O3 ferroelectric film. By adopting the method, requirement for equipment is simple, the experiment condition can be easily achieved, the doping amount can be easily controlled, and the ferroelectric performance of the film can be greatly improved, so that the prepared Bi(1-x)RExFe0.96Co0.02Mn0.02O3 ferroelectric film has good uniformly, less current leakage and high remanent polarization.