A windshield wiper includes a wiper post and a connection unit which is used to connect the wiper post and a wiper arm. The wiper rod has a bottom connected with a rubber blade. The wiper post has an opening at a central portion thereof, a recess at a central bottom of the opening, and a resilient plate disposed on the recess. One end of the resilient plate is connected with the bottom of the opening, and another end of the resilient plate is suspended above the recess and has an engaging buckle. The opening has protruding steps which are formed at two sides of the resilient plate. The protruding steps each have a vertical surface formed with a lumpy section. The connection unit is detachably mounted in the opening of the wiper post. The connection unit has a bottom formed with a protruding platform corresponding to the opening. The protruding platform has a slide trough at a central portion thereof corresponding to the resilient plate. Two sides of the protruding platform each have a vertical surface formed with a lumpy portion corresponding to the lumpy section of the opening.