Objective：To investigate the efficacy of flexible ureteroscope in the treatment of lower calyceal renal calculi. Methods：To－tally 42 patients with lower calyceal renal calculi were treated with Holmium laser lithotripsy through flexible ureteroscope including 36 cases of primary lower calyceal calculi and 6 cases of secondary calculi. Results：All cases were successful operated except one case due to lower urethral stricture. The primary clearance rate was 82.92%（35/41）. There was no serious complication except blood－ing in one case. Conclusion：Holmium laser lithotripsy through flexible ureteroscope is a safe and effective treatment for lower calyceal renal calculi. And it may become the first treatment option for lower calyceal renal calculi with diameter less than 2 cm，especially for lower calyceal renal calculi without obstruction.