The invention provides a polyvinyl chloride thermal suspension polymerization terminating agent and application thereof. The terminating agent is prepared from the following components by mass percent: 20 to 40 percent of alky substituted dithiocarbamate, 10 to 30 percent of perchlorate, and the balance of deionized water. According to the polyvinyl chloride thermal suspension polymerization terminating agent, under the synergistic acceleration effect of the alky substituted dithiocarbamate and the perchlorate, the free radicals and initiator in the polymerization reaction can be rapidly eliminated, the polymerization reaction can be rapidly terminated, the low-molecular-weight polyvinyl chloride molecules, the branch-chained polyvinyl chloride molecules, the terminal dual-bond polyvinyl chloride molecules and the polyvinyl chloride molecules with an allyl chloride structure can be greatly reduced, so that the thermal stability and thermal aging whiteness index of the finished productresin can be increased; and the terminating agent is simple in preparation method, cheap in raw material and capable of decreasing the production cost of polyvinyl chloride.