The technology of grid-connected harmonic current suppressor in STATCOM system was introduced and the design methods of L type and LCL type harmonic current suppressor was studied. The effect of each parameter variation was analyzed, which affect the performance of L type and LCL type harmonic current suppressor based on bode diagram method of Matlab. At the same time, on the condition of maintaining the same value of the total inductance, the contrastive analysis on the performance of L type and LCL type harmonic current suppressor was studied. The conclusion that the performance of LCL type harmonic current suppressor is better obviously. The simulation contrastive verification was combined with simulation model. At last, the experimental platform based on DSP was set up. The experiment waveforms which were recorded and was analyzed by FFT, the result show the validity of the theoretical analysis and simulation performance above.