Abstract:  In view of the tailings features with sulphur-rich and ultra fine particle from a certain lead and zinc mine, strength experiments of total-tailing backfill material proportion were carried out. It is indicated that the pyrite-rich tailing has an obvious impact on the strength of the filling body. During the hardening process of the filling body, it first causes the slow solidification of the filling body, which produces an upper limit value on the short-term strength, and then the expansive hydrate generated leads to the cracking of the filling body, resulting in deterioration of the later strength. Due to the superfine particles, the mass concentration of meeting the strength requirements needs to be higher under a reasonable cement-sand ratio. It is suggested that the slurry concentration should not be less than 76%, where high short-term and late strength can be obtained as the cement-sand ratio is 1∶8. There is a threshold value for the cement-sand ratio, which is considered to be the minimum value for generating sufficient hydration products, of not less than 1∶25. At a higher mass concentration, and with the increase of cement-sand ratio, the increase of long-term strength are more significant.