The Dongbeizhai Gold Mine is located in the Songpan seismic belt， dominated by strongly water-sensitive phyllite strata with extremely complex stratigraphic conditions. Collapse， diameter reduction， rockfall， and low core recovery are the main problems faced by core drilling in this area， greatly affecting the drilling efficiency and hole formation.This article aims to address the formation characteristics of the project and the characteristic of the construction equipment， which is all fully hydraulic drills. Through extensive and in-depth research， based on the lessons learned from previous construction experience in the mining area， by optimizing equipment performance， improving equipment adaptability， using multi-diameter drilling and a inhibitor flushing fluid system with good adaptability to the formation， combined with comprehensive drilling techniques such as follow-up drilling， pump-free dry fishing， and diamond wireline three-layer tube coring， the construction efficiency and quality have been improved， and good results have been achieved. This comprehensive drilling construction technology has good promotion and application value for the efficient use of full hydraulic drills in the construction of complex strata such as strongly water-sensitive phyllite in the northwest region of Sichuan.