The invention discloses an H250 sex-pole harmonic excitation generator. The H250 sex-pole harmonic excitation generator is structurally characterized in that the rear end of a front end cover and the front end of a machine base are connected and fixed through bolts, a stator iron core is pressed into the machine base, a shaft sleeve, a front bearing, a cast aluminum fan, a rotor iron core, a rear bearing and an exciter rotor are respectively installed on a spindle, an exciter stator iron core is fixed in a rear end cover, and the rear end cover and the rear end of the machine base are connected and fixed through bolts. The front bearing and the rear bearing serve as two supporting points of the generator. A connecting spring piece is installed on the shaft sleeve, the rear end of a connecting ring and the front end of the front end cover are connected and fixed through bolts, and the front end of the connecting ring is connected with an oil engine. The H250 sex-pole harmonic excitation generator has the advantages that the generator is good in steady-state performance, low in rotation speed, small in vibration, reasonable in structure, small in occupied space and light in weight, is of a double-support structure and meanwhile is provided with the connecting spring piece, and connecting modes for the generator and a diesel engine are more varied.