External contracting projects are one of the main forms of economic cooperation between China and countries along "The Belt and Road". Strengthening the country environmental research of the contracted projects along the "The Belt and Road" is conducive to reducing risks and improving the success rate. Based on the existing research, new business environment factors and the characteristics of infrastructure contracting projects are taken into consideration. A comprehensive environmental evaluation system for project contracting countries with 6 environmental factors and 33 indicators is constructed and the entropy value method is used to quantitatively study 64 countries' environment of contracting project. Then this paper tests the result of the application of entropy value method with Spearman and clusters comprehensive evaluation value through SPSS 19.0. The empirical evidence shows that:Firstly, the infrastructure environment and economic factors are the most important factors influencing Chinese enterprises' decision of foreign project contracting country selection; Secondly, project contracting environment is very different and imbalance among the countries along "The Belt and Road", it is better in southeast and south Asia, secondary in Central and eastern Europe and West Asia and North Africa, worse in East Asia, Central Asia and the commonwealth of independent states; Lastly, according to the comprehensive evaluation value, the countries' environment of contracting project is divided into four types:good, better, worse, and worst. This study has positive empirical evidence for Chinese construction enterprises to actively develop foreign contracted projects in the countries along "The Belt and Road", and also provides valued reference for the implementation of Chinese "The Belt and Road" and "go out" strategies.