Pump head structure. The pump body adopts double-layer pump casing (double-layer metal structure inside and outside), the double pump casing is vertical split type, and the water outlet position can be rotated by 8 different position devices according to 45 ° distance. In order to effectively avoid shaft seal leakage, the combination of power seal, packing seal or mechanical seal is adopted. Labyrinth gap seal is set between impeller and back guard plate, which greatly reduces the leakage of slurry to stuffing box and effectively ensures the reliability of seal. The impeller is equipped with back blades to discharge the reflux slurry in time, thus improving the volume ratio, reducing the reflux and erosion, and improving the service life of the overflow parts. In order to facilitate maintenance and disassembly, a disassembly ring is provided to prevent shaft cutting due to failure of disassembly.