【Abstract】 Objective To investigate effects of the analgesic effect and its effect on the accuracy of diagnosis. Methods A retrospective study was performed on 67 cases of acute abdominal pain treated by the department of emergency medicine t of The Affiliated Hospital of Southwest Medical University from February 2017 to July 2017. We compared the effect and analgesic effect of the early use of nefopam on the diagnostic accuracy of acute abdomen. Results The accuracy of the diagnosis accuracy for the pain control group and the placebo were 875% and 911% (x2= 0012, P = 09). We have found the no significant difference between the two groups. After treatment, the median of 05 hours, 1 hour and 2 hours of VSA score was 4, 62, 6;5, 6 (P = 001, P = 001, P = 0031) in the two groups. Conclusion The early use of Nefopam in acute abdomen does not affect the accuracy of the diagnosis. Nefopam is effective and has a long working time. Because of moderate analgesia effect, it’s suitable for early pain relief of acute abdomen.