Disclosed in the present invention are a preparation method for an olefin epoxidation catalyst and applications thereof. The method comprises: loading an auxiliary metal salt onto a silica gel carrier, and carrying out a drying treatment to the silica gel carrier; loading a titanium salt (preferably TiCl4) onto the silica gel carrier by a chemical vapor deposition method; calcining to obtain a silica gel on which the auxiliary metal oxide and Ti species are loaded; obtaining an catalyst precursor (Ti-MeO—SiO2 composite oxide) by water vapor washing; loading alkyl silicate (preferably tetraethyl orthosilicate) onto the surface of the catalyst precursor by a chemical vapor deposition method and calcining the catalyst precursor to obtain a Ti-MeO—SiO2 composite oxide with the surface coated with a SiO2 layer; and carrying out a silylanization treatment to obtain the catalyst. The catalyst can be applied to a chemical process of propylene epoxidation to prepare propylene oxide, and has an average selectivity to PO up to 96.7%, the method of the present invention and the applications thereof have industrial application prospects.