Abstract: ［Abstract］Objective　To compare the clinical effects of paraffin-embedded cell block and smear in the differential diagnosis of benign and malignant pleural effusion. Methods　80 cases of patients with pleural effusion from May 2012 to May 2015 were randomly selected, each pleural effusion sample was divided into 2 parts, 1 part paraffin-embedded sections were detected by cell block method, and 1 part by cell smear．Results　The positive rate of cytology cell block paraffin-embedded sections 28.8%（23/80）was significantly higher than smear 22.5% （18/80），P <0.05, the detection rate of cytopathology diagnosis of cancer 32.5%（26/80）was significantly higher than smear 20.0%（16/80），P <0.05；Among the 80 cases of specimens，31 cases were bloody ascites and pleural effusion，of which 13 cases were malignant，the positive rate was 41.9%；56 cases were non-bloody chest ascites, of which 11 cases were malignant, the positive rate was 19.6%. The positive rate of fluid cytopathology diagnosis of bloody abdominal cavity was significantly higher than non-bloody ascites and pleural effusion，P＜0.05．Conclusion　The clinical effect of paraffin-embedded cell block in the differential diagnosis of benign and malignant pleural effusion is better than smear.