The invention provides a multi-stage magnetic field electric-arc ion plating method for a lining positive-bias step-shaped pipe and belongs to the technical field of material surface treatment. According to the multi-stage magnetic field electric-arc ion plating method, cleaning of the inner wall, polluted by large particles and deposited ions in a multi-stage magnetic field filtering device, of the pipe is achieved, and the loss in the transferring process of electric-arc plasma is avoided. The multi-stage magnetic field electric-arc ion plating method comprises the following steps that (1) a to-be-film-plated workpiece is placed on a sample table in a vacuum room, a relevant power source is switched on, and an external water-cooling system is started; and (2) thin film deposition is conducted, specifically, when the vacuum degree in the vacuum room is smaller than 10 <-4> Pa, working gas is pumped in, the gas pressure is adjusted, a film plating power source is started; meanwhile, a bias power source is used for attracting the electric-arc plasma at an outlet and conducting energy adjustment; through stop shielding of the lining positive-bias step-shaped pipe, the inhibiting effect of a positive-bias electric field and the filtering effect of a multi-stage magnetic field, large particle defects are effectively eliminated, and transferring efficiency of the electric-arc plasma is guaranteed; and needed technological parameters are set for thin film preparation.