The invention belongs to the technical field of preparation of
trisilylamine, and particularly relates to a preparation method of
trisilylamine, which comprises the following steps: firstly, preparing monochlorosilane from monosilane and
trichlorosilane under the action of a catalyst, rectifying and purifying reactants to obtain monochlorosilane, and purifying the monochlorosilane to obtain
trisilylamine; adding the obtained monochlorosilane and
ammonia gas into a low-temperature reactor according to a certain proportion, and reacting for a certain time; and filtering, rectifying and purifying the reaction liquid to obtain the high-purity trisilylamine. The method for preparing the trisilyl amine is low in cost, the raw materials are simple and easy to obtain, the
reaction conditions are mild, and the reaction is simple and controllable.