The present disclosure belongs to polymercaptan compounds and application fields thereof, and particularly relates to a polymercaptan compound and a preparation method thereof, a curing agent, a resin composition, an adhesive and a sealant. The polymercaptan compound is represented by formula (I), wherein R1, R2, R3, R5, R7 and R8 are each independently selected from one of a hydrogen atom, an alkyl group with 1-5 carbon atoms and an alkoxy group with 1-5 carbon atoms, R4 and R6 are each independently selected from an alkylene group with 1-5 carbon atoms, and m and n are each independently 0, 1, 2 or 3.