Abstract: The proven gold reserve accumulates over 91 t in the Yixingzhai Gold Deposit,and it is the largest gold deposit in Shanxi Province.3 types of ore bodies develop in the district,including quartz vein type,altered porphyry type,and altered breccia type.Altered breccia-type mineralization is hosted by 4 cryptoexplosive breccia pipes.The Tietangdong cryptoexplosive breccia pipe is the largest one,and the potential for mineralization and further exploration of which are important issues for mine enterprise.Based on detailed outdoor geological survey and lithology logging in the Tietangdong cryptoexplosive breccia pipe, this study figures out its formation process, which includes:no skarn breccia stage in the lower part (Ⅰ),felsite and massive skarn stage in the upper part (Ⅱ),calcite-specularite(-garnet) vein stage(Ⅲ),magmatic breccia stage with skarn fragments(Ⅳ),quartz porphyry dikes stage (Ⅴ) and quartz-sulfide vein stage (Ⅵ).There are genetic connections between the skarn section and the felsite in the upper Tietangdong cryptoexplosive breccia pipe.Both formed at 138-139 Ma.The breccia section where felsite occurs is an important prospecting target in the Tietangdong cryptoexplosive breccia pipe.