Objective To compare the effect of puncture needles with different diameter on percutaneous biopsy for transplant kidney under ultrasound guidance. Methods A total of 82 cases underwent percutaneous renal biopsy for transplant kidney under ultrasound guidance,and were divided into two groups based on the diameters of puncture needles, Group 18 G (n =31)and Group 16 G (n =51).The effect of biopsy and complications were compared between the two groups. Results Compared with Group18 G,Group16 G used less puncture needles and obtained more glomeruli (both P <0.01).The qualified rate of renal specimens in Group 16 G was significantly higher than that of Group 18 G(P <0.05). There was no significant difference in postoperative complications between the two groups (P >0.05 ).Further stratified comparison was conducted,and the results showed that complications of the two groups were not statistically significant in case of puncture with 2 needles or 3 needles (both P >0.05). Conclusions There is similar safety of 16 G puncture needle and 18 G puncture needle to perform renal biopsies under ultrasound guidance.Under the allowable condition of patients,16 G puncture needle is superior to 18 G puncture needle and realizes high quality of renal specimens.