To provide an electronic component mounting system and an electronic component mounting method which can prevent a mounting failure due to positional error in a height direction of a substrate and ensure mounting quality.The electronic component mounting system includes a plurality of electronic component mounting devices connected to one another and mounts an electronic component on a substrate to manufacture a mounting substrate. A print test device for testing the substrate after solder printing measures a height position of a height measurement point set on the upper surface of the substrate 4 by a height measuring machine 22 and outputs a measurement result as substrate height data. In a component placing step using an electronic component placing device, a control parameter for controlling a component placing operation of the placing head 32 is updated. Accordingly, it is possible to correct a variation of the height position of an individual substrate and to prevent a mounting failure due to positional error in the height direction of the substrate.