Abstract: With the acceleration of urban modernization, engineering activities are becoming increasingly frequent. It is necessary to analyze the geological conditions and evaluate suitability before urban planning and engineering construction. The suitability of engineering construction is affected by multiple interrelated factors in different degrees. Taking the downtown Huangshan City for example, the paper introduces the application of GIS- and AHP-based grey evaluation method in suitability evaluation from the perspective of geoenvironment. The method first selects the influencing factors closely related to the suitability as evaluation factors, then determines the weight by AHP on the basis of the qualitative evaluation on single factor, and finally evaluates the suitability comprehensively with the grey evaluation method. The effect proves to be good, which can be extended to the same kind of evaluations.