The coating material feasibility and reliability in the prevention and control of remnant material in microwave circuits was studied. The vacuum chemical vapor deposition method to deposit Parylene C film on the product surface was proposed. The experimental results show that the film can effectively control the remnant material with a diameter of less than 1 mm， and improve the pass rate of particle impact noise detection test. In the meantime， the film has good compatibility with assembly processes such as welding， gluing， interconnecting， and cleaning and meets the reliability requirements. The film has high insulation strength and excellent insulation protection for microwave circuit. Consequently， the arylene C film has application feasibility and potential value in microwave products.