At present the global climate warming increasingly, global warming with the greatnegative impact has made human realize the importance to reduce greenhouse gasemissions.In order to slow down climate change,all works of life in the global are committedto save energy. Our country’s road infrastructure with high coverage, more than90%highwayuse semi rigid base pavement structure.Therefore this paper analysis in detail the greenhousegas emissions of semi-rigid base construction process, and finds out the potential of emissionsreduction during the semi-rigid base construction.Based on road life cycle assessment(LCA), the paper analyses of greenhouse gasemissions during the construction process of our country’s typical semi-rigid base--the thecement stable macadam. The system boundaries of the roads life cycle is set for: extractionand manufacture of raw materials, transportation, mixing, paving, rolling and water sprayingmaintenance seven stages, not considering the process of operation period and reconstructionstage.First of all, the paper detailed analysis of the various stages of the greenhouse gasemissions, given the gas emissions source list; Secondly, to different emissions source givethe method of quantitative emissions; Finally, will the method given above applied to projectcase.The raw materials considered in this paper including: cement, gravel and electricity. Theresearch results show that the whole of cement stable macadam construction process’sgreenhouse gase emission mainly comes from raw material acquisition phase,and the cementproduction process account for more than90%;The greenhouse gas emissions duringconstruction stages mainly comes from all kinds of construction machinery fuel emissions;And construction stage accounting for relatively few—less than10%.