In a board placement method and system, a PCB panel having multiple interconnected PCB units and a vacant space is placed on a work surface of a reference platform. The work surface has an opening corresponding to the vacant space. The reference platform has a micro-adjusting unit, which includes a support seat disposed in the opening and movable along three directions. The support seat is used for placement of a good PCB unit. The current positions of the PCB panel and the good PCB unit are measured so as to calculate a target position of the good PCB unit and an error between the target position and the current position of the good PCB unit. The micro-adjusting unit can drive the support seat to move so as to move the good PCB unit to the target position. The good PCB unit is then fixed in the vacant space.