An automatic shoulder strap reversing device comprises a machine frame and a shoulder strap reversing assembly arranged on the machine frame. The shoulder strap reversing assembly comprises an installation frame, a shaft sleeve, a shoulder strap reversing power piece and a pushing and ejecting piece. The shaft sleeve comprises a fixed end and a hollow free end connected with the fixed end. The fixed end is installed on the machine frame through an installation frame. The free end extends away from the installation frame. The shoulder strap reversing power piece is installed on the machine frame. One end of the pushing and ejecting piece is connected with the shoulder strap reversing power piece. The other end of the pushing and ejecting piece is coaxial with the free end and is arranged in the free end in a telescopic mode through the shoulder strap reversing power piece. Through the shoulder strap reversing assembly, automatic shoulder strap reversing replaces existing manual shoulder strap reversing, work intensity is lowered, production efficiency is greatly improved, the production cycle is shortened, and economic benefits are further improved.