Abstract: The equilibrium structure of economic geography is the result of combined effect of both internal and external forces, so this paper no longer regards region as "point" without spatial dimensions and holds that trade cost exist in both inside and outside of the region, and local technology spillover effect and environmental pollution effect are also different within and outside a region. Based on these foundations, the new economic geography model developed in this paper shows that:Firstly, the strengthening of local technology spillover effect and trans-boundary environmental pollution effect promotes industrial agglomeration whereas the strengthening of local environment pollution effect and the trans-boundary technology effect lead to industrial dispersion, and the increase of intraregional trade freeness also help to form a decentralized spatial pattern. In addition, the core-periphery equilibrium may be exist under the circumstance that the substitution elasticity between industrial goods is too low or too high. Secondly, not only can the stable internal asymmetric equilibrium exist alone, but also co-exist with the internal asymmetric and core-periphery equilibrium or with the symmetric and core-periphery equilibrium when the trade freeness is within a certain range. Thirdly, the stable symmetric equilibrium may exist in both situations whether trade freeness is low or high, even under certain conditions, the symmetric structure is the only stable equilibrium structure no matter how the trade freeness changes.

Key words: trade cost, technology spillover, environmental pollution