Objective:To observe the phenomenon of complete Freund’s adjuvant (CFA)-induced inflammatory pain and explore the analgesic effect of 7-nitroindazole(7-NI) on dorsal root ganglion(DRG),and briefly discuss its analgesic mechanism. Methods:Ten microliters of CFA were injected into the plantar surface of the hind paw of the mice to produce inflammatory pain models,von Frey filaments were used to determine 50% paw withdrawal threshold(PWT) adopting by up-and-down method which can be regarded as an evaluation criteria for the pain behavior test. The changes of 50% PWT were tested by microinjecting 10 -滋g 7-NI into DRG of the mice. Detect the expression of calcitonin gene related peptide (CGRP) in CFA-induced,7-NI treated and neuronal nitric oxide synthase(nNOS) knock-out models by Western blot. Results: Compared with DMSO group,50% PWT significantly increased in 7-NI group during 2~12 h after CFA inducing. The expression of CGRP increased after CFA injection,this effect could be reversed by 7-NI administration or nNOS knock-out. Conclusion: Microinjection of 7-NI into DRG could produce analgesia in inflammatory pain mice. Increased expression of CGRP might be the downstream mechanism resulted from NO mediated nociceptive effect in dorsal root ganglion.