For a long time, planners get used to apply qualitative analysis and subjective knowledge to define urban green space system. Lacking support of quantitative analysis, the incomplete inventory will result in subjective evaluation, low pertinence. And the required depth and level for planning will not be strong enough. This study strives for introduce ecological suitability evaluation to urban green space system, derives the supporting theory, framework, and evaluation model. By using GIS, Luancheng green space system is generated based on the ecological suitability analysis. Also, this study shows that green space system planning is more operational and reliable based on ecological suitability evaluation.