MoS2　nanosheets　(NSs)　have　been　found　to　possess　the　peroxidase-like　activity　and　widely　used　in　colorimetric　sensors.　However,　the　catalytic　active　sites　of　MoS2　NSs　are　still　unclear.　Herein,　MoS2　NSs　with　sulfur　defects　were　prepared　using　the　molten　salt　method　at　different　heating　temperature　(800　degrees　C-1100　degrees　C)　and　following　by　ultrasonic　exfoliation.　With　the　increasing　of　heating　temperature,　the　crystallinity　of　MoS2　NSs　is　improved,　accompanying　with　the　decrement　of　S/Mo　atomic　ratio.　The　increment　of　sulfur　defects　in　MoS2　NSs　remarkably　enhances　the　peroxidase-like　activity　of　MoS2　NSs.　The　catalytic　inhibition　by　phosphate-containing　molecules　further　verifies　the　catalytic　active　sites　of　MoS2　NSs　are　Mo　atoms　with　sulfur　defects.　Finally,　the　peroxidaselike　activity　of　sulfur　defect-rich　MoS2　NSs　was　applied　for　the　colorimetric　detection　of　H2O2　and　the　inhibitor.　This　work　helps　to　understand　the　peroxidase-like　catalytic　mechanism　of　MoS2　NSs.