Laboratory test about cemented backfill indicated that the influence of the percentage of sulfur in tailings on the initial strength,later strength and stability of cemented tailings backfill in airtight state is not obvious,but,even the sulfur content is low to 4% the cemented tailings backfill in exposed state undergo cracking until entirely breaking.It was pointed out that when mining sill pillar intervening pillar the cemented tailings backfill with high sulfur content in stope and first-mined slice should not be exposed more than 50 d,otherwise it is oxidized to destruction.