Abstract: Shield construction technology had been widely used in urban subway construction, ground subsidence or collapse problems caused by shield construction had been highly attentioned. Based on the research results at home and abroad, analysis of the main reasons of surface subsidence or collapse caused by shield construction, it was put forward to carry out detection technology studies for holes behind the shield. Chengdu Metro Line 3as an engineering example, combined with lessons of Metro Line 1 and Line 2, accorrding to a large number of field tests, the comprehensive detection technology suitable for detection holes behind the shield was got, for special Chengdu Metro across the sand and gravel formations with complex physical and mechanical properties. The comprehensive detection technology including pre-construction, construction and post-construction detection technologies, with inside and outside detection technologies, a system was initially formed, which was worthy of similar projects and in-depth study.