中文摘要：

河谷型城市由于受周边山体的限制和制约，其人口容量计算极具特殊性。本文首先通过承载力的研究进展分析，在相关研究的基础上，以典型河谷型城市兰州为例，分析了河谷型城市人口容量的主要刚性制约因素为河谷空间、生态环境及水资源。接着以最短边理论分析为依据，在此基础上计算得出兰州市四个主城区的适宜人口容量为207—227．44万之间，最大人口容量在338．24～367．72，万之间。根据2006年年末人口统计数字，兰州市主城区城关区、七里河区、西固区、安宁区四区的人口总数已达205．75万人，十分接近计算所得适宜人口容量207万的低值。最后提出兰州市跳出河谷，拓展新城的战略构想。

英文摘要：

Taking the representative city Lanzhou as an example, the main influence factors of population capacity in the valley - city were analyzed. Valley land space, eco - environment and usable water resources were the three deciding factors of population capacity in the valley - city. According to the restriction theorem, the four main districts＇optimal population capacity and maximal population capacity in Lanzhou were calculated. The optimal population capacity was between 2.07 million and 2.27 million and the maximal population capacity is between 3.38 million and 3.68 million. According to the statistics of Lanzhou government, 2006, the total population of the four main ditricts, Chengguan, Qilihe, Anning, Xigu had already gotten up to 2. 0575 million, almost catched up with the bottom of optimal population capacity 2.07 million we had calculated in this paper. So, there have no space for the further population growth. The basic conclusion was that developing new towns were the city＇s future stratagem.