The invention relates to a preparation method of tricyclohexyl phosphine, which comprises the following steps: reacting a cyclohexyl Grignard reagent and phosphorus trihalide, dropwisely adding a saturated strongly-acidic weakly-alkaline inorganic salt water solution at low temperature to carry out quenching, adding tetrafluoroboric acid to prepare a salt, and resolving the salt with triethylamine to obtain the tricyclohexyl phosphine, wherein the cyclohexyl Grignard reagent is prepared by carrying out Grignard reaction on halogenated cyclohexane and magnesium metal under inert gas shielding. According to the invention, the product is subjected to after-treatment by a chemical process; the tetrafluoroboric acid firstly reacts with tricyclohexyl phosphine to form a salt to completely extract the tricyclohexyl phosphine from the reaction solution, and the salt is resolved with the triethylamine. The invention has very obvious beneficial effects, and greatly enhances the preparation yield; and the prepared product has the advantages of high purity, high quality and low preparation cost.