The invention relates to a system and method for measuring the position of a planar motor rotor based on grating scales and two-dimensional sensors, and belongs to the technical field of semiconductor equipment. The measuring system adopted by the invention comprises an X-direction grating scale, a Y-direction grating scale, three laser heads and three two-dimensional PSD sensors, wherein the X-direction grating scale and the Y-direction grating scale perform measurement on major travels of the planar motor rotor in the X-direction and the Y-direction respectively, each laser head and two-dimensional PSD sensor pair can measure the displacement of the rotor in two specified directions of the X-direction, the Y-direction and the Z-direction, and the three laser head and two-dimensional PSD sensor pairs can cover motion information of the rotor in the X-direction, the Y-direction and the Z-direction. According to the measuring method provided by the invention, position computation for the rotor is performed based on data acquired by the measuring system, and all six-degree-of-freedom displacement of the planar motor rotor in a planar motor stator fixed coordinate system can be acquired.