The invention relates to a preparation process for a solid-state composite electrolyte, belonging to the technical field of methods or apparatuses used for directly converting chemical energy into electric energy. The preparation process comprises the following steps: step 1, preparing a conveyor belt; step 2, applying a paste onto a grid; step 3, bonding the grid with a protective film; step 4, cutting the protective film; step 5, pressing the grid and cutting the protective film again; step 6, carrying out drying in a drying chamber; and step 7, acquiring the solid-state composite electrolyte. Such a technical solution in the invention effectively solves the problem that protective films are prone to crease and inconvenient to cut during preparation of solid-state composite electrolytesin the prior art. According to the preparation process in the invention, the protective film is straightened by the rotation of rollers and is then cut, and drying is carried out after lamination of the grids through pressing, so good effect is obtained.