A hybrid exciting synchronous generator (HESG) is analyzed in this paper, including its particular structure and operation principle. A permanent magnet generator is used for providing the main output and a homopolar inductor alternator is used for regulating the terminal voltage. The electromagnetic field computation and the performance analysis of the HESG are carried out by using three-dimensional finite element method. A 1.5 KW, 2000 rpm to 9000 rpm, 8-pole and 9-slot HESG is tested to verify the flux control capability. Experimental results show that it is possible to obtain a voltage from 64% to 126% of the voltage generated only by PM with the adjustment of the exciting current. And the variation range of the output voltage can be narrowed greatly while the speed of the generator varies from 2000 mm to 9000 rpm.