二嗪磷（Diazinon），学名硫代磷酸-O,O-二乙基-O-(2-异丙基-4-甲基-6-嘧啶基)酯，是一种广谱性有机磷杀虫剂。

纯品为无色油状液体，略带香味。工业品为灰色至暗棕色液体。难溶于水，能溶于石油醚，可与乙醇、丙酮、二甲苯混溶。对酸、碱、热不稳定，对光稳定。在水及稀酸作用下会缓慢水解，变为高毒的四乙基硫代焦磷酸酯。

Diazinon (IUPAC name: O,O-Diethyl O-[4-methyl-6-(propan-2-yl)pyrimidin-2-yl] phosphorothioate, INN - Dimpylate), a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company (later Novartis and then Syngenta). It is a nonsystemic organophosphate insecticide formerly used to control cockroaches, silverfish, ants, and fleas in residential, non-food buildings. Diazinon was heavily used during the 1970s and early 1980s for general-purpose gardening use and indoor pest control. A bait form was used to control scavenger wasps in the western U.S. Diazinon is used in flea collars for domestic pets in Australia and New Zealand. Residential uses of diazinon were outlawed in the U.S. in 2004 but it is still approved for agricultural uses. An emergency antidote is atropine.