The invention discloses a composite modifier for surface modification of calcium carbonate. The composite modifier is prepared from a modifier A and a modifier B according to a mass ratio of (8-10):(5-7). The composite modifier has a better modification effect than existing single-component modifiers; and compared with existing multi-component (two or more) composite modifiers, the composite modifier of the invention has the advantages of simple and uncomplicated components, excellent modification effect, and cost reduction.