Considering the externalities influence on metropolitan economic development， this paper estimates and de- composites 285 metropolitan cities Total Factor Productivity （TFP） from year 1990 to 2008. We find that technical progress and technical ef iciency improvements are the major determinants of urban TFP growth， while the agglomeration externality factors， such as factor allocation ef iciency and scale efficiency are major hindrances for TFP. Urban economic density has two opposition infl uences on urban TFP: manufacturing spatial agglomeration reduces urban TFP， high distribution of industrial fi rms has “congestion” ef ects； population spatial density has inverse-U shape ef ect on urban TFP growth. Population factor is still the driving factor for Chinese urban TFP growth， and population-manufacturing's spatial “co-agglomeration” phenomena has positive ef ect in our s tudy