In the light of safe mining evaluations for the first mining district which is cut by fault F8 in the thirteenth mining level in the Zhaogezhuang coal mine, Kailuan, this paper adopts such methodology as measured ground stress, traditional and special rheological rock mechanics experiments, and three-dimensional visual numeric modeling using FLAC3D. A lot of weakening effect mechanics parameters of fault materials have been obtained. The paper also discusses their weakening effect mechanisms, controlling factors, and presents a new concept of the time weakening effect of fault materials under coal bed. The concept develops and enriches basic theory of water-bursting in coal mine. As a result, different safe mining schemes for the first mining district at the thirteenth level in Zhaogezhuang mine have been predicted and evaluated.