The invention discloses a mechanical stereo garage and an automobile conveying method thereof. The mechanical stereo garage comprises a getting in and out garage room, an electric control room, multi-layer parking places, a lifting system, a rotary transverse moving vehicle, an automobile conveyor, a lifting driving system, a transverse moving driving system and a conveying system, and the lifting system comprises a lifting platform. The mechanical stereo garage is characterized in that the lifting platform of the lifting system is provided with a running rail where the transverse moving vehicle moves transversely; the transverse moving vehicle is provided with a rotary structure; the rotary structure comprises a rotary frame, a rotary support, a gear and a conveyor running rail. As lifting, transverse moving and turning around of automobiles can be completed synchronously, automobile taking and storing time is shortened by means of the stereo garage, the number of devices is decreased, the site area of the getting in and out garage room is reduced, the number of fault occurring points is decreased, and positive social economic significance and definite technological advance are achieved.