The invention discloses a water quality monitoring ship. The water quality monitoring ship comprises an unmanned ship body; at least one group of detection units are arranged on the unmanned ship body; each detection unit comprises a water collection pipe, a water collection pump, a flow divider valve connected to the water collecting pipe, and a first detection cavity and a second detection cavity which are connected to the flow divider valve; a first sensor and a second sensor are arranged in the first detection cavity and the second detection cavity respectively; each flow divider valve comprises a valve body internally provided with a cavity; a cylindrical valve core is arranged in each cavity; a rotating shaft is mounted at the axis of each valve core; each rotating shaft is mounted at the power output end of a motor; and each valve core can rotate under the driving of the motor. According to the water quality monitoring ship, unnecessary loss of the sensors can be avoided, so that the monitoring cost can be saved, and the replacement frequency of the sensors can be reduced.