This paper analyzes the current problems of the serious damage to the common dwellings and historical key buildings in Bayu ancient town and the insufficient understanding of the complexity of the protection work, established the basic idea of traditional residential building modular protection design, and further proposed the specific modular protection method which is composed of current building element data collation, common residential type renovation design, and special building type key design. The longtan Ancient Town in Chongqing is taken as an example for research and exploration.