The invention discloses a plate punching and shearing machine used for machining office furniture. The plate punching and shearing machine comprises a trimming table. A punching, shearing and piercingdevice is fixed to the top end of the trimming table through a U-shaped supporting frame. A horizontal longitudinal sliding groove is formed in the trimming table. A horizontal oil cylinder is installed at one end of the horizontal longitudinal sliding groove. One end of the horizontal oil cylinder is connected with a plate conveying and sliding base arranged in the horizontal longitudinal sliding groove in an inserted manner. A plurality of L-shaped fixing blocks are installed on the plate conveying and sliding base. When the horizontal oil cylinder is started, the plate conveying and sliding base can drive plates fixed to the plate conveying and sliding base to be moved to the suitable position to be trimmed, labor force and time are saved, the stroke of a piston rod of the horizontal oil cylinder is controlled by an oil cylinder controller, thus the position of plate trimming and piercing can be more accurate, pressing is carried out firstly, then punching, shearing and piercing are carried out, the trimming and piercing speed is higher, the machining efficiency and quality of the plates are improved, a punching and shearing cutter and a piercing head of the punching, shearingand piercing device can carry out trimming and piercing on the plates at the same time, the machining efficiency of the plates is improved greatly, noise is low, and the machine has the advantages ofsaving energy and being low in cost.