The invention provides a low-pressure plasma spraying method for a TiN coating. The low-pressure plasma spraying method comprises the steps: spraying Ti powder under a low-pressure condition by using a high-power plasma spray gun; and carrying out plasma spray-physical vapor deposition by taking nitrogen as a plasma working gas and a reaction gas to achieve the TiN coating. The TiN coating prepared by using the low-pressure plasma spraying method is of a columnar structure, high in component purity, fine in crystal grain, dense in structure and capable of effectively improving the performance of the surface of a workpiece. A nitriding layer exists between the coating and the workpiece, so that the bonding strength of the coating and the workpiece can be effectively improved. The low-pressure plasma spraying method is simple in process, high in deposition efficiency and suitable for rapidly spraying the TiN coating on a large area.