Abstract: The core of urban planning engineering geology investigation is the evaluation of land construction suitability.In present code of urban planning investigation,it is employed single-factor nonnumeric evaluation method.Incorporating with the fuzziness and uncertainty of affecting factors for evaluation of land construction suitability,the fuzzy mathematics theory is applied after comprehensive analysis.the two-grade fuzzy evaluation model is taken via establishing evaluation index system which incorporates selection of main influential factors and determining the evaluation criterion for each impacting factor.The comprehensive fuzzy evaluation approach is primarily drawn on the determination of the membership idea and weight number for the factors.We use the expert evaluation method and the formula method in evaluating both the membership idea and weight number.The comprehensive fuzzy evaluation calculating process is illustrated with a case study.The afformentioned approach,which is applied into the evaluation for urban planning land construction suitability from the engineering geology and environmental geology perspectives,is a beneficial exploration.With the gradual deepening and advancing for urban planning engineering geology investigation,we strongly believe the specific approach will have had its applying prospect in the near future.