从城市化水平的Logistic方程出发,推导出如下关系式:城市化速度最快时期的城市化水平=城市化水平的饱和值÷2,最大城市化速度=城乡人口增长率差×城市化水平的饱和值÷4。对概念的定义和方法的应用给出了限定和说明。借助美国1790¹960年的城乡人口普查数据验证了上述推导结果。利用上述关系分析了中国的城市化水平数据,结论是:2005年前后城市化速度达到峰值,由此判断中国的城市化水平饱和值为80%左右;2005年之后,中国的城市化水平增长速度在理论上应该减缓,在实际工作中不宜继续推动加速过程。

New relations on urbanization level and velocity are derived from logistic equation of urbanization process:（1） Z_max（V）=max(Z_t)/2,and（2） max(V_t)=kmax(Z_t)/4,where max(Z_t) denotes percentage of capacity at end of terminal stage,max(V_t) denotes maximum of urbanization velocity on the trend line and k denotes urban-rural growth difference.The first formula implies that urbanization velocity becomes a maximum when urbanization level becomes half of the saturation value,and the second formula means that the maximum velocity of urbanization equals the product of urban-rural growth difference and the saturation value of urbanization level.The US urban and rural population data by census from 1790 to 1960 are applied to validating/verifying the above-mentioned theoretical relations. We can predict the saturated level of urbanization by means of the maximum velocity of urbanization;meanwhile,we can also achieve the goal of expected saturated value by control of urbanization velocity.As the relations are derived from logistic growth model,the precondition of applying the formulae is that urbanization process in a region follows logistic rule.In addition,the maximum velocity of urbanization should be estimated by trend line instead of observed data because of random stochastic disturbance. The formulae are applied to China's data of urbanization level from 1978 to 2000.Conclusions are drawn as follows:（1） Saturation value of China's urbanization level is predicted as around 79.26%.China's level of urbanization reaches the peak value round about 2005,when level of urbanization is 39.63% or so.（2） Urbanization of China should be decelerated from 2005 forth/onwards.Population of China is more than 13 hundred million nowadays.It is hard for such a large country of population to make its urbanization level exceed 80%.According to China Statistical Yearbook 2005,the urbanization level of China is about 41.76%.If the current urbanization velocity holds the line,it might lead to grave consequences,such as over-urbanization,pollution of the environment,ecological disturbance,and various urban problems.