The invention belongs to the fields of instrument maintenance tools and application and particularly relates to a cleaning kit with a split/splitless sample injection inlet and an application method of the cleaning kit with the split/splitless sample injection inlet. The cleaning kit comprises a component I and a component II, and a groove (7) is formed in the lower end of a cylinder (5) of the component II and consists of an upper gripper (6) and a lower gripper (8). The application method includes detaching sample injection inlet accessories, using the component I for brushing, using the component II for wiping, rinsing and drying the inner sides of sample injection inlet welding parts and the like. The cleaning kit with the split/splitless sample injection inlet and the application method of the cleaning kit with the split/splitless sample injection inlet have the advantages that the component I can brush off residual pollutants on the inner sides of the welding parts under the action of external force, and after the groove of the cylinder in the component II is filled with degreasing cotton dipped with an organic solvent, the residual pollutants on the inner sides of the welding parts can be thoroughly wiped in a high fit manner under the action of external force; with the groove consisting of the upper gripper and the lower gripper, the degreasing cotton cannot shed when moving on the inner sides of the welding parts up and down, and accordingly the cleaning kit is simple and convenient to operate and thorough to clean.