Abstract:The government green purchase is widely considered to be an effective means of promoting sustainable consumption. However, how to identify the greener product is the biggest obstacle of government green purchase and it has not been well solved. A quantitative evaluation method is provided to measure the green degree of different products of the same use function with an indicator system established, which includes fundamental indicators, general indicators, and leading indicators. It can clearly show the products' green extent by rating the scores of different products, which provides the government a tool to compare the green degree of different products and select greener ones. A comprehensive evaluation case of a project purchasing 1635 desk computers in Tianjin government procurement center is conducted using the green degree evaluation system. The environmental performance of the products were assessed quantitatively, and the evaluation price, which was the bid price minus the discount (the discount rate was according to the total scores attained by their environmental performance), and the final evaluation price ranking from low to high in turn is supplier C, D, E, A, and B. The winner, supplier C, was not the lowest bid price or the best environmental performance, but it performed well at both bid price and environmental performance so it deserved the project. It shows that the green extent evaluation system can help classify the different products by evaluating their environment performance including structure and connection technology, selection of materials and marks, prolonged use, hazardous substances, energy consumption, recyclability rate, etc. and price, so that it could help to choose the greener products.