 the paper suggests that by underscore 4 Br underscore 4 is a suitable candidate for dissipationless electron transport due to its large band gap, appropriate insulating substrates and multiple conducting channels. First principles calculations show that the topological edge states of single layer by underscore 4 Br underscore 4 are well preserved on an intrinsic insulating substrate and can be fully decoupled at the boundary of multi-layer by underscore 4 Br underscore 4 by constructing a stair stepped edge. The paper suggests that an ideal QSH insulator can be prepared by nano fabrication on the cleave surface of lead by underscore 4 Br underscore 4 single crystal. This article was offered by Jin Jianjiu, Wan Xiangfeng, Gu Yibin Liu, and others.