The first stage project of line 1 of Chengdu Metro mostly passes through waterrich sandy cobble ground，which contains a small amount of large boulders. In the paper, the authors make analysis and discussions on several key issues related to the application of muddingtype EPB shields to sandy cobble ground in Chengdu, which includes the treatment of the large boulders, the wearing of the cutter heads and the cutting tools and the prevention and control of mud bursting.