The invention discloses a double-layer composite aluminum film gas release type preparation process, and belongs to the field of aluminum films. According to the double-layer composite aluminum film gas release type preparation process, through the arrangement of a two-way air cylinder, before a double-layer film is extruded, on one hand, gas is blown into the double-layer film, a gas release layer can be formed in the double-layer film, blowing force is generated on the overlapped double-layer films to force the double-layer films to be separated when the double-layer films are close to the blowing cylinder, so that the bulging part containing bubbles is integrated with other parts, the condition of individual bubble bulging is effectively reduced, then the double-layer films are integrated again in cooperation with air suction operation, the bubble amount in the double-layer films is remarkably reduced, the situation of being scraped because of bulging can be effectively avoided, and the quality of the finished products is significantly improved in comparison with the prior art. On one hand, the air blowing cylinder is bulged during air inflation, so that the fluff layer above the air blowing cylinder is in frictional contact with the upper-layer film to generate static electricity, the stability of the double-layer film which is overlapped again is effectively improved, and the quality of the composite aluminum film finished product is further improved.