The invention discloses a high water-blocking flame-retardant composite film for lithium battery packaging, which comprises a protection layer, an adhesive layer, a passivated aluminium foil layer anda heat-seal layer, wherein the protection layer is a single-sided or double-sided plated nylon film or polyester film, and a plating thickness is about 1 to 5mu m; the heat-seal layer is an adheringheat-seal CPP (chlorinated polypropylene) integrated layer which is of a three-layer structure, and has a thickness of about 30 to 80mu m; the three-layer structure comprises an adhering action layer,a supporting action layer and a heat-seal action layer. The invention further provides a multi-layer spraying film process for preparing the composite film for lithium battery packaging. According tothe composite film prepared by the invention, water absorption of nylon is effectively reduced; hydrolysis resistance of an adhesive layer between the nylon and an aluminium foil is reinforced; moreover, by the multi-layer co-extrusion spraying film process, once forming from the raw material to the finished composite film is implemented, single production of a CPP film and an adhesive attachingprocess are omitted, and production cost and equipment investment are effectively reduced.