High titanium slag was a perfect raw material to produce synthetic rutile.Microwave-assisted leaching removes some of its iron content, as well as producing high percentage of TiO2.Life cycle assessment of designing and manufacturing decisions has attracted significant attention in recent years.In this paper, greenness evaluation index and system of microwave-assisted leaching process were established.The effects of the life cycle assessment variables such as the resource consumption, environment impact, cost,time and quality were investigated systematically, and the concept of green degree was applied in the production of synthetic rutile.