D-STATCOM is wildly used for its’ ability to compensating reactive power and suppress harmonic. D-STATCOM paralleling operation may amplify the load harmonic current. Thus its’ usage is confined. In order to enhance its’ advantage and avoid the disadvantage, the D-STATCOM compensating nonlinear load system was analyzed by circuit equivalence. For voltage-source type nonlinear loads, the harmonic equivalent independence decrease with the harmonic order, harmonic amplification becomes more serious. Series rector can reduce harmonic equivalent independence, thus, harmonic amplification can be suppressed. Simulation shows D-STATCOM may not will worked without additional measurement by the influence of harmonic amplification; series reactor can suppress the effect and improve D-STATCOM performance efficiently.