Objective To investigate the synergism and attenuation effects of Scapharca Subcrenata Extraction on NP chemotherapy in model mice. Methods The models of nude mice were induced with A549 cell line xenograft. The tumor inhibiting rates, body weight, food intake, hematology and blood biochemistry index were determined to evaluate the synergism and attenuation effects of Scapharca Subcrenata Extraction (125、250、500 mg/kg, i.g) on NP chemotherapy. Results Compared with NP chemotherapy group, the tumor inhibiting rates, body weight, food intake, white blood cell number were increased and glutamate pyruvate transaminase, glutamic oxalacetic transaminase and urea nitrogen were decreased markedly in NP chemotherapy plus Scapharca Subcrenata Extraction groups. Conclusion Scapharca Subcrenata Extraction has a remarkable synergism and attenuation effects on NP chemotherapy.