Objective To study the different therapeutic effect of ultrasound guided percutaneous needle aspiration and percutaneous catheter drainage on bacterial liver abscess. Methods 98 patients with bacterial liver abscess were recruited. Of 46 patients with abscess above five centimeters in diameter, 21 were treated by needle aspiration and 25 by percutaneous catheter drainage. Of 52 patients with abscess under five centimeters in diameter, 30 were treated by needle aspiration and 22 by percutaneous catheter drainage. The time of vomica extinction, the hospital day and the time of hemogram and body temperature being normal of the two methods after operation were compared. Results Percutaneous catheter drainage was superior to needle aspiration in the hospital day and the time of vomica elimination patients with abscess above five centimeters in diameter（P＜ 0.05）, but similar to needle aspiration in patients with abscess under five centimeters in diameter（P>0.05）. The differences of the two methods were not statistically significant in the recovery time of hemogram and body temperature for all cases, and in hospital day and the time of vomica elimination for patients with abscess under five centimeters in diameter（P>0.05）. Conclusions Ultrasound guided percutaneous catheter drainage is the first choice treatment for bacterial liver abscess above five centimeters in diameter, and needle aspiration is the first choice treatment for that under five centimeters in diameter.