Abstract: Provided are a high temperature and chloride corrosion resistant NiCrTiAlSi/La2O3 coating at a flue gas side of a waste incineration power generating boiler and a preparation method thereof. The method comprises the following steps: (1) preparing a composite powder; (2) uniformly grinding the composite powder to obtain a spherical composite powder, then drying the spherical composite powder; (3) cleaning and roughening a surface of a substrate; (4) using a thermal spraying technique to spray a primer layer on a heating surface; (5) using a thermal spraying technique to spray the spherical composite powder onto the primer layer; and (6) cooling. The coating obtained by the method comprises a composite coating spray-coated on a surface of the primer layer. A rare element in the form of La2O3 is added to the coating to purify a grain boundary of the coating.