Abstract: Objective To conduct a field epidemiological investigation of a poisoning incident caused by the accidental ingestion of wild mushrooms in Chongqing, and to identify the mushroom species and toxin type, so as to provide references for the management and clinical treatment of such incidents. Methods Epidemiological investigation methods were used to collect case data. The type of mushroom was preliminarily identified based on morphological characteristics. Further molecular identification was conducted. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to detect the psilocybin and psilocin toxins in the mushroom samples, and psilocin was also detected in the plasma of the patients. Results Three individuals were poisoned in this incident. The clinical manifestations included dizziness, fatigue, and numbness in the upper body, and no abnormalities were observed in liver or kidney function indicators. Based on field epidemiological investigations, morphological identification, and molecular identification, the suspected mushroom was determined to be Gymnopilus dilepis. Laboratory testing detected psilocybin and psilocin in the mushroom samples, and psilocin was also detected in the plasma of the patients. The clinical manifestations were consistent with the laboratory test results, conforming to the diagnostic characteristics of psilocybin poisoning. Conclusion Gymnopilus dilepis is the mushroom responsible for this poisoning incident, with psilocybin and its metabolite psilocin being the primary toxins. The clinical presentation is predominantly characterized by neurological symptoms, with no significant impairment of liver or kidney function. Education on the identification of wild mushrooms should be strengthened to prevent the occurrence of similar incidents.