A lithium ion battery composite diaphragm comprises first particles and second particles, and a binder which is less than 5wt%, the lithium ion battery composite diaphragm is characterized in that: the first particles and the second particles have different particle size compositions, the first particle has a first particle size r, the second particle has a second particle size r', wherein the particle size r and the particle size r' satisfy a relationship defined in the description; the first particles are prepared from at least one or more of egg shells, duck egg shells, goose egg shells andother bird or amphibian egg shells; the second particles are shells and abalone shells; a first particle layer, a second particle layer and the binder are adopted to form a film, an integrated lithium ion battery composite diaphragm material is formed, an inorganic material is not easy to fall off, meanwhile, a particle material plays a full role, and in comparison with a lithium ion battery inorganic diaphragm in the prior art, the lithium ion battery composite diaphragm of the invention has the technical effects of high stability, strong high temperature resistance, good thickness control and capability of preventing pore passages from being blocked by the binder.