An item picking and replenishment method is provided. According to the item picking and replenishment method, an item position corresponding to at least one item is output according to an order by a host, and the item position is received by a processing unit of a picking vehicle. A moving signal is generated by the processing unit according to a current position of the picking vehicle and the item position. A rotary encoder of the picking vehicle is used to move the picking vehicle to the item position according to the moving signal. The item is obtained from a shelf by an insertion fork of the picking vehicle. The insertion fork is disposed on a placement layer of a placement shelf, and the placement layer is a tilted layer.