The invention designs a continuous mixing device capable of adjusting concentration of bacteria solutions. The main structure of the device comprises a diaphragm type metering pump, a water pump, a Y-shaped filtering device, a ball valve, a backpressure valve, a non-return valve, an adjusting valve, a pulse damper, a float type flowmeter and a pipeline type static mixer, wherein a bacteria solution feeder comprises the non-return valve, the Y-shaped filtering device, the diaphragm type metering pump, the pulse damper and the backpressure valve; the diaphragm type metering pump is used for adjusting the relationship curved line of scales of a handwheel and flow rate in order to accurately adjust the flow rate of the bacteria solutions; the water flow rate is accurately controlled through acontrol valve and the float type flowmeter; and water and the bacteria solution are fully mixed through the pipeline static mixer and then flow out. With the adoption of the device, the concentrationof the bacteria solutions can be accurately adjusted in real time; and moreover, the bacteria solutions can be continuously massively supplied; in addition, the device has the characteristics of beingsimple and stable in structure, uniform to mix, stable to work, convenient to operate, and low in cost, and reducing the working intensity.