Drugs for acute postoperative pain and breakthrough cancer pain are still urgent on clinical. LPM3480392 is a G-protein-biased ligand at the μ-opioid receptor and showed potent analgesia in nonclinical studies. Two phase I studies of LPM3480392 were conducted in healthy Chinese male volunteers to explore its tolerability, pharmacokinetics, and pharmacodynamics under single ascending doses (Study I 0.1-3.0 mg, 30 min) and different infusion time (Study II, 0.6-1.0 mg, 2-15 min). There was one serious adverse event (AE) observed in Study II, and the rest AEs were mild or moderate in severity and resolved by the end of the study. Plasma LPM3480392 maximum concentration (C ) (under lower infusion rate) and area under the plasma concentration-time curve (AUCs) were generally increased with dose. Moreover, LPM3480392 at dose of 0.6 mg under 2 min infusion rate elicited effective analgesia as the peak effect within 10-30 min, which measured by cold pain test and pupillometry. These findings suggest that LPM3480392 could be a potential treatment for acute pain management.