Ｏｂｊｅｃｔｉｖｅ　To observe the effect of ultrasound-guided thoracic paravertebral block on dermatomes of sensory blocked in patient undergoing pleural effusion.　Methods　Sixty patients with multiple fractured ribs are divided in two groups. Each group included 30 cases, patients in group P combined with pleural effusion while patients in group N were non pleural effusion. Both two groups were given the general anesthesia combined with ultrasound-guided thoracic paravertebral nerve block(TPVB), and received patient controlled intravenous analgesia(PCIA). Dermatomes of sensory block were recorded at 1 min and 15 min after administration locate anesthetic. The amount of remifentanil, MAP, HR and operative time were recorded. The pain analog scale(VAS) during rest and movement were observed at 1, 4, 8, 24, 36 h after operation.　Results　In group P and group N, dermatomes of sensory block at 1 min after administration locate anesthetic were (4.1±1.2), and (3.3±0.7) respectively. Dermatomes of sensory block at 15 min after administration locate anesthetic were (5.8±1.4), (5.0±1.0) respectively. The numbers of blocked dermatomes in group P were larger at 1 min after administration locate anesthetic and 15 min After administration locate anesthetic(P<0.05). There were no significant difference in MAP, HR and VAS between the two groups.　Conclusions　TPVB offered Patients with pleural effusion for wider dermatome of sensory blocked. TPVB was safe and effective for patients undergoing pleural effusion.