The invention discloses a direct-axis current set control method for a permanent magnet synchronous motor adopting a small-capacity thin-film capacitor. The small-capacity film capacitor replaces a large-capacity electrolytic capacitor in a traditional power circuit; compared with a traditional motor drive system, a small-capacity film capacitor frequency conversion system is smaller in size and lighter in weight. Influence of fluctuating bus voltage on quadrature and direct-axis reference currents is not required to be considered, and the method is simpler and more effective by comparison with a traditional direct-axis current set manner; specific subharmonic components in quadrature and direct-axis voltage set values are filtered out through a wave trapper, a current controller is an internal model controller, a repetitive controller or a PR controller, and quadrature-axis current of the motor can track period set signals quickly.