Abstract: The popular site selection methods at current cannot be used to make quantitative analysis on the influence factors from the alternatives or partly.In order to solve this problem，a new method,influence factor quantification and weighting method is put forward，which can fully or quantitatively analyze the alternatives of all influence factors.The specific approaches are as follows:firstly，the value of influence factors is calculated out according to quantitative factors of construction investment and operating costs.Then，the probability and weighting for the natural，economic and social aspects of conditional influence factors are given，and the qualitative value of the influence factors is obtained by multiplying the probability with the weighting.Finally，the value of comprehensive influence factors is gained by sum of both of multiplying the quantitative influence factors and qualitative influence factors with their weighting separately.The method with the highest influence factors value will be optimum.The optimum method is used to optimize the site selection and transportation scheme of H iron dressing plant in Mongolia built by a Chinese company.The results indicates that among the two alternative sites and six alternative transportation schemes，value points of comprehensive influences factors corresponding to transportation scheme 1~3 for site 1 is obviously higher than that of transportation scheme 4~6 for site 2，meanwhile the value points of comprehensive influence factors of transportation scheme 3 is the highest among the six transportation alternatives.The conclusion is that site 1 matching with transportation scheme 3 is the best choice.

Key words: Influence factor quantification and weighting methods, Site selection of dressing plant, Transportation method selection of dressing plant