Aims: TPN171, a novel phosphodiesterase 5 (PDE5) inhibitor, is under development for the treatment of male erectile dysfunction (ED) and pulmonary arterial hypertension (PAH) in China. Kidney clearance is a major drug elimination pathway. A pharmacokinetic study of TPN171 in patients with impaired renal function is necessary. Methods: To investigate the pharmacokinetics (PK) properties and safety of TPN171 in individuals with severe renal impairment and normal renal function, an open-label, single-dose, parallel-group phase 1 study was conducted in 8 volunteers with severe renal impairment and 8 volunteers having normal renal function, who received TNP171 tablets (10 mg) in the fasting state. TPN171 plasma concentrations were measured up to 72 h thereafter. The maximum plasma concentration (Cmax), the area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUC0-t) and AUC extrapolated to infinite time (AUC0-∞) were calculated and compared between groups. Results: As compared with those with normal renal function, the elimination half-life (t1/2) of volunteers with severe renal impairment, was prolonged, resulting in a decrease in clearance rate. The geometric mean ratios (GMRs) for Cmax, AUC0-t and AUC0-∞ were 74.25% (90% confidence interval [CI], 56.18%–98.13%, p = 0.081), 138.06% (90% CI, 107.82%–176.78%, p = 0.037), and 137.31% (90% CI, 107.53%–175.33%, p = 0.038), respectively, and the adverse reaction rate showed no significant difference. All adverse events were mild intensity, and no volunteer was discontinued in this study. Conclusions: No TPN171 dosage adjustment is required for patients with mild to severe renal impairment.