The invention belongs to the field of machine vision target pointing, and discloses a vision guide hard real-time pointing device based on an onsite bus. The device comprises a bottom plate, a visionmodule, a slave station module, a master station module, a servo control module and a target pointing module, wherein the vision module, the slave station module, the master station module, the servocontrol module and the target pointing module are sequentially connected on the bottom plate. The vision module collects and displays the image information and processes the image information to obtain actual position coordinates, and transmits the actual position coordinates to the slave station module. The slave module and the servo control module realize information interaction with the masterstation module through an onsite bus communication protocol. The servo control module calibrates and displays a position range corresponding to the image boundary point, and transmits the position range to the master station module, and the master station module establishes the corresponding relation between the position coordinates and control parameter values, and converts the actual position coordinates into control parameter values and transmits the control parameter values to the servo control module, thereby realizing the control of the target pointing module. The device guarantees the real-time communication of a vision system and a motion control system, and achieves the independent application without a computer.