A positioning and locking device of a movable working table is applied to the technical field of hydraulic machines and comprises transverse positioning blocks, an end positioning block, movable positioning devices and a base plate. The two transverse positioning blocks, the end positioning block and the two movable positioning devices are fixed to a lower cross beam A through bolts, and the lower portion of the end positioning block protrudes to be embedded into the lower cross beam A; the base plate is fixed to the end positioning block through a bolt; and each movable positioning device is composed of a support, a lug base bottom plate, a hydraulic cylinder, a proximity switch, a lug base, a guide sleeve, a locking pin, a lining plate and a sliding plate. Pistons of the hydraulic cylinders are connected with the locking pins through the lug bases, and the locking pins slide in the guide sleeves; and cylinder bodies of the hydraulic cylinders are connected with the lug base bottom plates through the lug bases. When a hydraulic machine carries out compressing, peripheral locking blocks can resist horizontal pushing force in any direction, and risks of slipping of the working table can be completely avoided. The positioning and locking device of the movable working table is simple in structure, convenient to use and convenient to maintain and adjust, and can resist horizontal force.