With the concept and connotation of urban ecological infrastructure, this paper establishes an index system for evaluation of urban ecological infrastructure. The paper uses the mean square error method to calculate the weight of each index and the gray correlation theory to construct an evaluation index system consisting of two subsystems, i.e. natural and aritificial ecological infrastructure. The index system includes 9 factors and 33 indicators. The 9 factors are atmosphere, green space, wetland, transportation, energy supply, water supply and drainage, telecommunications, environmental health, and safety of disaster prevention. With the index system a case study was made in Liupanshui City, Guizhou Province. The evaluation results are as follows: the comprehensive index values of the poorest, poor, medium, good and superior infrastructure are 0.678 8, 0.750 4, 0.724 3, 0.611 0 and 0.523 5, respectively. That shows that as a whole the ecological infrastructure in Liupanshui City is of poor grade, in which the natural ecological infrastructure is of medium grade with an index value of 0.828 5, and the aritificial ecological infrastructure is of poor grade with an index value of 0.791 2. Through the evaluation and analysis, we can have a basic understanding of the current situation of the ecological infrastructure in Liupanshui City and the results can be for scientific reference of the programming and construction of Liupanshui City. Also the index system can be applied to others cities.