The invention provides a mobile water quality monitoring sensor launching device. The mobile water quality monitoring sensor launching device comprises a sensor launching bracket, the sensor launchingbracket is provided with an inclined working plane, a power roller is arranged at a top end of the inclined working plane, the power roller is connected with a synchronization motor, multiple conveying rolls are arranged on the inclined working plane, a sensor cylinder is arranged on the conveying rolls in an inclination way; multiple groups of water quality monitoring sensors are arranged in thefront section of the sensor cylinder; the end part of the front section of the sensor cylinder is opened, a grating is formed at the opening; the rear section of the sensor cylinder is a cavity structure, and a digital-to-analog conversion (ADC) module is arranged in the cavity structure; the ADC module transmits digital signals of multiple groups of water quality parameter data to the external through digital transmission lines; the data transmission cable is coiled on the power roller as a traction wire coil of the sensor cylinder, the power roller is quantitatively controlled through the synchronization motor, and the launching depth of the water quality monitoring sensor is determined and controlled. The launching depths of multiple groups of water quality monitoring sensors can be accurately controlled.