Abstract: High gas flow of 10.⁴×10⁴m³/d has been obtained in the first shale gas exploration well Puluye 1 in Puguang area, marking a major breakthrough in shale gas exploration of the Middle Jurassic Qianfoya Formation in the northeastern Sichuan Basin. By using lab test data such as shale gas content, geochemical, petromineralogical, and reservoir characteristics, accumulation conditions and enrichment rule of shale gas in Well Puluye 1 are analyzed. The study results show that: (1) The laminated felsic clay rock of semi-deep lake facies was continuously developed in No. 3 thin layer of the first member of Qianfoya Formation in Well Puluye 1, with the average desorption gas content of 0.58 m³/t, total gas content of 1.58 m³/t, average TOC of 1.13%, Type Ⅱ₁-Ⅱ₂ organic matter, average R_o of 2.03%, and average porosity of 3.8%,which is a sweet spot interval for shale gas exploration; (2) The high-quality shale of semi-deep lake-deep lake is the basis for shale gas enrichment; (3) The key factors for the enrichment and high production of shale gas include high intensity of hydrocarbon supply by the highover mature shale, good fluidity of gas cracked by crude oil, and high reservoir space and methane adsorption capacity of the organic pores;(4) The intensively developed High-angle fractures, bedding micro fractures and cleavage fissures support to increase the reservoir space and permeability of shale, which are important conditions for high shale gas production of Qianfoya Formation in Well Puluye 1. The above results enrich the understanding of oil and gas reservoir types, reservoir space characteristics, enrichment and high production rules of the high-over mature shale in the Jurassic Qianfoya Formation in the northeastern Sichuan Basin, which has important guiding significance for shale oil and gas exploration in the study area.