Objective To investigate the safety and feasibility of preoperative non-indwelling catheter in primary unilateral total knee arthroplasty (TKA) without tourniquet . Methods From January 2016 to January 2017, a total of 60 patients undergoing primary unilateral TKA surgery were randomly divided into preoperative non-indwelling catheter group (group NIC, n=30) and indwelling catheter group (group IC, n=30) . The patients in group NIC were not retained catherter, and the patients in group IC were retained catherter. All patients did not use tourniquet. The time of first urination, the volume of first urination, and the occurrence of urine retention, urinary irritation symptoms and urinary tract infection of patients in two groups were analyzed. The incidence of venous thrombosis of the lower extremity was also recorded. Results There were statistical differences (P<0.05) between group NIC and group IC in the time of first urination [(3.2±0.6) vs. (4.5±1.8) hours] and urine volume [(262.5±29.4) vs. (391.6±50.2) mL], but there was no significant difference (P>0.05) between the two groups in urinary retention (6.7% vs. 16.7%), urinary tract irritation (33.3% vs. 23.3%), or urinary tract infection (0.0% vs. 16.7%). Conclusion Preoperative non-indwelling catheter in primary unilateral TKA without tourniquet is safe and feasible.