The invention discloses an under-well pulp generator used to supply power to the driller, which comprises a turbine, a driving axle, a speed changer, an inner magnetic rotor of magnetic coupler, a baffle muffle, an outer magnetic rotor of magnetic coupler, and a generator. Wherein, said under-well pulp generator uses magnetic coupler technique, uses pulp to drive turbine to rotate the driving axle; and via the speed changer to rotate the inner magnetic rotor of magnetic coupler; the outer magnetic rotor of magnetic coupler can synchronously rotate, to rotate the rotation axle of generator, and cut the magnetic line, to realize the non-contact power transmission; when the discharge is higher, it can utilize the slip effect generated by the inner and outer magnetic rotors to protect the generator; the speed changer works in oil; therefore, the generator can work reliably under well. The under-well pulp generator can be combined with data platform to communicate.