In order to solve the problem of synchronously and tinily injecting agent into the multiple pipelines, a high precision injecting device with double pumps is proposed. Double pumps can balance load, standby for each other, and provide unified power for multi-channel injecting; the injecting strategy is PID-PWM, which replaces valve position adjusting with the electromagnetic valve switch control to achieve accurate injecting, and in turn has good rapidity. Application examples indicate that, the injecting device can realize independent, accurate and synchronous multi-channel injecting with high control precision and low hardware cost.