The invention relates to a method for improving quality of a doped DLC (diamond-like carbon) film. A shielding device is arranged around a workpiece before plasma CVD (chemical vapor deposition) of the doped DLC film on the workpiece, and an opening is formed in the shielding device and directly faces a plasma outlet; during plasma CVD of the doped DLC film, the shielding device does not rotate with the workpiece but is equipotential with the workpiece. According to the method provided by the embodiment, the shielding device is mainly arranged around the rotating workpiece during deposition, so that the position with extremely uneven plasma density distribution nearby the circumference of the workpiece is shielded, only deposition of high-density ions of plasma right facing the plasma outlet is received, the uniformity, binding force and the like of the finally obtained film are greatly improved, and the method is quite suitable for industrial mass production.