Ecological suitability assessment has been listed as a important part of content in regional environmental impact assessment according to <Technical guidelines for environmental impact assessment of development area> (HJ/T2003), which only requires to set up three-hierarchy indicators system but without appointed approaches to integrate these indicators. In current practice, several approaches have been attempted to apply, such as arranging and comparison technology, analytic hierarchy process and fussy evaluation. However, due to the subjectivity in weight evaluation, these approaches are afraid of the objectivity of their results. Catastrophe progression method is an approach dealing with multiple indicators integration, which is suitable for the complex system decision because of its simpleness and objectiveness. With a case study on Zhenjiang New Area, the basic principle for catastrophe progression method and its applying steps in ecological suitability assessment are introduced in this paper. The case study shows the applicability of catastrophe progression method in ecological suitability assessment. What is more important, through analyzing and contrasting the mathematical essence of the three above-mentioned approaches, catastrophe progression method demonstrates obvious comparative advantages of two following respects mainly: on one hand, it does not use any weight, only need to arrange indicators in an order of important degree according to the inherent logic relationship among indicators, this avoids making the subjectivity of the artificial weight evaluation in very large limit; on the other hand, as a technological approach that combine qualitative analysis and quantitative analysis together, catastrophe progression method is not only suitable to judge whether a piece of land is suitable for its using patterns, but also provide models to calculate out the concrete number value of ecological suitability, and help to carry on the quantitative contrast of ecological suitability among different pieces of land. However, what should be pointed out objectively is, in the course of arranging indicators in the order of important degree and hierarchizing indicators, the artificial subjectivity in catastrophe progression method can’t be avoided completely, so it would be necessary to combine other technological approaches to improve the future application of catastrophe progression method in ecological suitability assessment.