The utility model relates to a spider uses key combination with rotor core hookup, the major key groove of placing major key and attached key is compound keyway structure, major key and attached key clearance and attached key and rotor punching clearance, but the radial magnitude of interference of effective isolation and the tangential magnitude of interference, the major key is the rectangle, be less than the notch in major key groove, and the tank bottom at the major key is equipped with rectangle time groove, the circle leans out the rectangle arch in the rotor punching, it is protruding slightly wide to compare the major key rectangle, it radially realizes the contact and adopts interference fit to guarantee rectangle arch and attached key, guarantee to leave the clearance simultaneously between tangential direction major key and attached key, reduce the rotor punching tank bottom fillet stress concentration of department and yoke portion magnetic density and loss. Subordinate to the key for sectional type combination air exercise taper key structure, increase rotor core axial direction's area of contact, the major key with subordinate to the key and be responsible for the radial and tangential magnitude of interference respectively. The utility model is suitable for a big torque motor, especially three generations nuclear power station circulating water pump motor can be used to trades such as nuclear power, metallurgy, seawater desalination.