At present, combining spatial clustering with spatial index is one of the techniques that could enhance data retrieval efficiency in the spatial database research. Based on the storage principles of spatial clustering and spatial index, K-Means clustering algorithm and the technical ideas behind improved algorithm are elaborated; the techniques of combining K-Means algorithm with spatial index method in spatial database are studied. Current research results of R-tree series spatial index technology based on K-Means algorithm air analyzed and their technical ideas for improving spatial retrieval efficiency and experiment results are described. The research shows that these techniques could enhance data retrieval efficiency to a certain degree. In the end, the future research trend of technique about combining clustering with spatial index is proposed.