The invention relates to the technical field of mechanical transmission, in particular to a chain transmission vertical bidirectional conveying device capable of operating continuously. The device is provided with a bottom-layer horizontal conveying belt and an automatic carrier loading and unloading device. The bottom-layer horizontal conveying belt is a horizontal conveying belt capable of achieving the automatic and accurate stop function; carriers needing to be conveyed upwards are placed at the entrance of the conveying belt, and the conveying belt carries the carriers and accurately stops in the loading position of a vertical conveying device. When the carriers needing to be taken down are at a certain height, a forklift frame of the automatic carrier loading and unloading device can be inserted forwards into the space under the carriers firstly; secondly, the automatic carrier loading and unloading device ascends vertically and takes down the carriers from carrier supports in the manner that the ascending speed of the forklift frame is higher than that of the carrier supports or the ascending direction of the forklift frame is opposite to the descending direction of the carrier supports; thirdly, the forklift frame drives the carriers to retreat and leave the work space of the vertical conveying device; and finally, the forklift frame descends to the initial height, the carriers are placed on the horizontal conveying belt on the two sides, and an unloading process is completed.