Old-style townhouses were popular in Taiwan during 1960-1980, many of these houses were poorly-designed and did not include enough fire protection equipment so that often caused large casualty and property loss on a fire incident. Hence, It is important to evaluate the townhouse fire protection capability. In this paper, the FDS(Fire Dynamics Simulator) software is utilized to develop a computer model for investigating the fire incident occurred in a townhouse of An-Kang Village, Longtan, Taiwan. The important parameters for the fire field characteristics-such as upper temperature distribution and CO concentration site. The simulation results are in good agreement with the post fire reports. The information calculated might be useful for the future fire safety assessment and fire protection engineering evaluation of the similar buildings.