The invention discloses a canned food top opening side arc thinning machine, and relates to the field of food processing. The canned food top opening side arc thinning machine comprises an I-shaped plate, and is characterized in that a supporting plate is fixedly connected with two sets of symmetric vertical rods, the upper side of the supporting rod is fixedly connected with two vertical rods ofa U rod, the upper side of the supporting plate is fixedly connected with first L-shaped rods, the symmetric first L-shaped rods form a rail, the symmetric first L-shaped rods are fixedly connected with a transverse plate, a transmission mechanism is arranged on the supporting plate, a thinning mechanism is arranged on the upper side of the supporting plate, a straightening mechanism is arranged on the upper side of the supporting plate, and a fixing mechanism is arranged on the upper side of the supporting plate. Through the machine, canned food top opening side arc thinning can be facilitated.