In order to meet the requirements of precision displacement feedback devices in microelectronics manufacturing equipment, a macro-micro composite grating ruler measurement system is proposed. First, the LabVIEW virtual instrument system is used for image data acquisition with high-speed. Then, the boundary of the amplified raster grating pattern is turned into lines with image processing method, which are later converted into pixel points, and the micro displacement in the motion process is compensated to improve the accuracy. The experiment results show that the proposed system can be used to keep the displacement error to 1.5 μm and the resolution to 0.275 μm with the motor speed of 1 mm/s and the distance of 100 mm. Compared with the traditional grating ruler measurement with moiré fringe electronically subdivided, the proposed measurement system can effectively eliminate the interference, such as grating scale damage, pollution, tilt and light source instability, on the measurement while maintaining the micron-level measurement accuracy, which is especially suitable for the long-distance measurement of open-scale grating ruler.