Objective To investigate the difficulties of building channel in ultrasound-guided percutaneous nephrolithotomy (PCNL).Methods Surgical processes of 45 patients underwent PCNL were recorded.The difficulties and causes in building channel were analyzed.Results In the process of building channel in PCNL,60 cases of difficulties happened,41.7％ (25/60) because of depth inaccuracy of puncture and dilation,18.3％(11/60) because of angle deviation of tract dilation,15.0％(9/60) result from nondilated collecting system,13.3％(8/60) because of lacking experience in ultrasound observation.Conclusions The most often encountered difficulties is depth inaccuracy of puncture and dilation in building channel,next is angle deviation of tract dilation.To improve technique detailes is the key to gain success.