Objective: To compare the efficacy and adverse reactions between 0.15% ropivacaine combined with sufentanil and 0.1% ropivacaine combined with sufentanil for labor analgesia in primiparous women with severe pain. Method: 195 full-term singleton primiparous women with severe pain (visual pain assessment [VAS] ≥6) were randomly allocated to two epidural analgesia groups using different drug formulations. One group received 0.1%  ropivacaine + 0.3 μg/mL sufentanil (control group, n=98). The other group was treated with 0.15% ropivacaine and 0.3 μg/mL sufentanil (experiment group, n=97). The following parameters were recorded: analgesia onset time; maximum VAS scores before analgesia, at 20 min after epidural administration, and during labor; number of analgesic pump presses; number of rescue analgesia events; total analgesic drug consumption; modified Bromage score; maternal satisfaction; duration of labor stages; mode of delivery; neonatal Apgar scores at 1 min and 5 min; and incidence of adverse reactions during labor analgesia, such as skin itching, nausea and vomiting, urinary retention, and fever. Result: The onset time of analgesia in the experimental group was significantly shorter than that in the control group (P<0.05). While the maximum VAS scores in both groups were significantly lower at 20 minutes post-epidural administration and during labor than before delivery analgesia (P<0.05), no statistically  significant inter-group differences were observed in VAS scores or in the number of pump compressions, rescue analgesia events, dosage of anesthetic drugs, modified Bromage score, or satisfaction ratings. Similarly, no significant differences were found between the two groups in the duration of labor, mode of delivery, and Apgar scores of newborns at 1and 5 minutes, or the incidence of pruritus, nausea/vomiting, urinary retention, or intrapartum fever. Conclusion: For primiparous women with severe labor pain, initial use of 0.15% ropivacaine combined with sufentanil significantly shortens the onset time, provides more comprehensive analgesic effects, achieves higher satisfaction, and does not increase short-term adverse reactions (including motor block) compared to the conventional 0.1% concentration regimen.