Objective To investigate the clinical effect of small needle knife to release Frohse arch on the treatment of posterior interosseous nerve entrapment syndrome. Methods From June 2015 to December 2018, 20 patients admitted to the second affiliated hospital of wenzhou medical university were diagnosed as postosseous nerve compression syndrome, and the Frohse arch was released by small needle knife therapy, and the effect and recovery after treatment were observed. The therapeutic effect of small needle knife and the recovery after treatment were observed. VAS score was used to evaluate the forearm pain score, and BMRC motor function scale was used to evaluate the muscle strength of the affected finger. Results VAS score was analyzed by variance test, and there were statistical differences between the first week after treatment and before treatment, between the fourth week after treatment and before treatment and between the first week and the fourth week after treatment (P < 0.05). The ranksum test of paired grade data was used to analyze the BMRC evaluation results, and the difference was statistically significant between the first week after treatment and before treatment, and between the fourth week after treatment and before treatment (P < 0.05). Conclusion Small needle knife treatment of postosseous nerve entrapment syndrome can significantly improve the hand function, has small trauma and good curative effect, and has great clinical application value.