The invention discloses a washing machine clamping device which comprises a left clamping piece, a right clamping piece and an opposite clamping mechanism. The opposite clamping mechanism comprises a clamping cylinder, a left rack, a right rack and a center gear. The left rack and the right rack are identical in length, tooth size and modulus. The clamping cylinder is fixed on the outside of a casing, and an output shaft of the clamping cylinder is fixedly connected onto the right clamping piece. The clamping device is reasonable in structure, the left clamping piece and the right clamping piece move synchronously when a workpiece is clamped, the workpiece is located in the middle of the clamping device when the workpiece is in the clamped state, the center of the workpiece and the center of the washing machine are located on the same line, excursion of the position of the workpiece is effectively prevented, device damage is avoided, and wide popularization and application are facilitated.