Abstract: Based on the inspection data and the relevant information of the old commercial buildings, the authors built a fire risk assessment system with the fuzzy grey comprehensive evaluation and the AHP which are the newest Information Processing Techniques. The software which runs in Visual Basic 6.0 according to the system were developed. This software could evaluate the fire risk indoor and determine the levels of fire risk of the commercial buildings. It not only overcomes the disadvantage of complex computing and long time for the manual calculation, but also provides a basis for how to transform the old commercial buildings. At last, the paper took of the evaluation of the fire risk of a old commercial building as an example to confirm the operability of the software.