The invention discloses a surface water runoff purifying plant cultivation block cutting device. A heating pipe is arranged on the periphery of a water inlet pipe and is of a spiral structure. One endof the heating pipe is connected with a transformer through a wire, and the other end of the transformer is electrically connected with the external mains supply through a wire. The heating pipe heats the water inlet pipe. The transformer adjusts the heating temperature. Four cutting blades are arranged on the outer portion of a transmission shaft. The four cutting blades are fixed to the transmission shaft at equal angles and are symmetrical about the central axis. Cutting blade sprayers are arranged on the root portions of the cutting blades. One end of each cutting blade sprayer is open and faces the blade face of the corresponding cutting blade, and the other end of each cutting blade sprayer communicates with the water inlet pipe. A driven wheel drives the cutting blades to rotate through the transmission shaft, the cutting blades conduct equal-distance cutting on materials, and meanwhile, the cutting blade sprayers clean the blade faces of the cutting blades. The surface water runoff purifying plant cultivation block cutting device is high in intelligence degree and stability, exerts small impact force on workpieces, guarantees that the workpieces are not damaged and has high yield.