Abstract: 【Objective/Meaning】Urban spatial compactness, an important indicator of urban spatial morphology and functional layout, is used to measure the compact and plumpness of land use in urban area.【Methods/Procedures】The comprehensive index system for the spatial compactness of cities, including 12 indicators involving into population, land use and transportation, were constructed in this article, and 8 center cities in urban agglomeration of Shandong Peninsula were analyzed by entropy method and system clustering.【Results/Conclusions】The results showed that:The urban spatial compactness of Shandong Peninsula was not high on the whole, and was with obvious spatial differentiation. The urban space compactness of Shandong Peninsula included high, medium and low levels according to the clustering analysis. The comprehensive spatial compactness of cities was gradually decreasing from the center, Jinan and Qingdao, to the surround. There was positive correlation between urban space compactness and population. It means the larger the population of city is, the higher the spatial compactness is.