The invention discloses a method for preparing a micro-nano-structured magnesium titanate active functional coating layer on a surface of a titanium-contained test piece, relates to a method for preparing a functional coating layer on a surface of a titanium test piece, and aims to solve the problem of abrasion and damage of joint bones easily generated on a titanium alloy micro-arc oxidation coating layer caused by high elasticity modulus of traditional titanium alloys. The method comprises the following steps: (1) firstly, the titanium-contained test piece is pretreated to obtain a pretreated titanium-contained test piece; (2) the acid washing is performed to obtain an acid-washed titanium-contained test piece; (3) the micro-arc oxidation treatment is performed to obtain the titanium-contained test piece having a micro-arc oxidation coating layer; and (4) the multi-arc ion plating is performed for the titanium-contained test piece having the micro-arc oxidation coating layer to finish the preparation of the micro-nano-structured magnesium titanate active functional coating layer on the surface of the titanium-contained test piece. The method is mainly used for preparing the titanium-contained test piece attached with the micro-nano-structured magnesium titanate active functional coating layer.