A new model on the relationship between the level of urbanization and connectivity of transport networks is derived as β=Az+ζ from Y.X.Zhou's model on the logarithmic relationship between the level of urbanization (Z) and that of economic development (X) and P.J.Taylor's model on the log-relation between connectivity of transport network (β) and the level of economic development (x'),the former take the form of z=alnx-b and the latter can be written as β=klnx'+φ,where x is per capita GNP,x' per capita income,percentage of population living in urban place,and β beta index,and A,ζ,a,b,k and φ are all parameters related.In the process of mathematical transformation,the linear relationship between per capita income (x') and per capita output value (x) was proved and used.We have xx',and the relationship is a key in the derivation.The new model is tested and verified using the data on the urbanization level and railway network of China.Based on the studies ut supra,an important conclusion can be reached that the construction of urban systems and development of transport network must be synchronized in order to consummate the geographical spatial structure in a region