in this section, applying the method, from abstract to specific and from history to present, it analyzes the operation mechanism of urbanization economy affected by market mechanism; puts forward four theories of urbanization economy from economic perspective, including agriculture surplus and comparison advantage; non-agricultural industry; agglomeration economy and spillover effect, on this basis of the theories, it, on one hand, analyzes two kinds of internal mechanism in the chronologic operation of urbanization economies : increasing mechanism of urbanization economies in urban output industry; and changing mechanism from specialization to integration, which are the representations of the evolution of " mart " development; on the other hand, it analyzes two internal mechanism of dimensional operation of urbanization economy : internal spatial enlargement mechanism of urbanization economies from monocentric city to multi-center city, and external spatial enhancement mechanism which represents city-regionalization and city-chain connection, the later two mechanism represent the evolution of " polis " development 這一部分,按照由抽象到具體和由歷史到現(xiàn)代的研究方法,分析了市場機(jī)制作用下的城市化經(jīng)濟(jì)運(yùn)行機(jī)理,從經(jīng)濟(jì)學(xué)角度提出了農(nóng)業(yè)剩余與比較優(yōu)勢、非農(nóng)產(chǎn)業(yè)、聚集經(jīng)濟(jì)、外溢效應(yīng)四大城市化經(jīng)濟(jì)定理;在此基礎(chǔ)上,一方面分析了城市化經(jīng)濟(jì)運(yùn)行沿時間增長的兩個內(nèi)在內(nèi)容提要機(jī)制:城市輸出產(chǎn)業(yè)的城市化經(jīng)濟(jì)增長機(jī)制和從專業(yè)化到綜合化的城市性質(zhì)變遷機(jī)制,它們主要表現(xiàn)為“市”發(fā)展的延續(xù);另一方面分析了城市化經(jīng)濟(jì)運(yùn)行沿空間增長的兩個內(nèi)在機(jī)制:從單中心到多中心的城市化經(jīng)濟(jì)運(yùn)行的內(nèi)部空間擴(kuò)展機(jī)理和表現(xiàn)為城市區(qū)域化、城市連綿體的城市化經(jīng)濟(jì)運(yùn)行的外部空間擴(kuò)展機(jī)理,它們主要表現(xiàn)為“城”發(fā)展的延續(xù)。