The invention relates to a two-valve injection method of a carbamide reducing agent, which is characterized in that a pipeline on a carbamide reducing agent box is connected with a filter in series, liquid flows across the filter through the pipeline due to the driving effect of pressure, the pipeline of the filter is connected with two electromagnetic flow control valves in parallel, the two electromagnetic flow control valves can independently or simultaneously start the connection with a pressure maintaining valve, the pressure maintaining valve is communicated with a carbamide reducing agent nozzle, and the carbamide reducing agent can be injected into an exhaust pipe with the aid of air. By using the conventional industrial electromagnetic flow control valves, the invention solves the problem on the dose of the original carbamide reducing agent based on different control logic, thereby having high reliability and practical value.