At present, eighty percentage aged people still reside in general housing in Taiwan area. How to let elder residents be capable of aging in place in general housing has been the responsibility of housing contractors and designers unavoidably. The implementation of aging in place is common target for many countries; the purpose of this paper is to study the designing technique which making existing housing spaces being able to response the need changing of elder residents' different living phases and supply continue care function. This will assist new housing construction or existing housing refurnishing to match the designing notion for aging in place. The research methodology is to simulate and assess life-cycle changing and housing space requirements by focus group discussion and to simulate the operation of housing space design focusing on countryside row house by the application of open building design method. The results of operation conclude as follows: 1) no matter what planning of elevator and stair, the space area of countryside row house constructing aging in place house was thirty-two pings, 2) the space of living room, dining room could be designed by separation and assembly, the space of storage could be designed by adaptation and the space of washroom could be designed by extension, and 3) there were obvious differences of space unit's flexibility for the possibilities of separation and assembly, adaptation and extension between the model of elevator and stair longitudinal planning and the model of elevator and stair transverse planning.