A new type of antimony mercapfide heat stabilizer--antimony mono(isooctyl thioglycolate) di(n-dodecanethiol) was prepared, and its apphcafion in polyvinyl chloride (PVC) plastics is discussed. The stabilizing effect of this product is better than the complex-stabilizer of Ca/Zn when it is used in soft PVC and than the complex-stabilizer of lead and dilauratetin dibutyl when it is used in hard PVC. Key words heat stabilizer; antimony mercaptide; antimony mono(isooctyl thioglycolate) eli(n-dodeeanethiol) ; polyvinyl chloride Antimony mercaptide is a new type of heat stabilizer for PVC, which has the following characteristics: high efficiency, nontoxic or harmfulless, low consumption and good attribute for processing, it can replace or partially replace the heat stabilizer of expensive org'anotin and has wide application I~-41 . We have got good results in researching into some antimony mercaptide salt, antimony mercaptan carboxylic ester and antimony dialkyl dithiocarbamate as heat stabihzer of macromolecular materials and extreme-pressure antiwear additive of lube I5-83 . This paper reports preparation of a new type of antimony mercaptide compound--antimony mono(isooctyl thioglycolate) di (n-dodecanethiol) and its application in PVC.