The present disclosure provides a grating including: a first substrate including stacked first and second electrode layers each including strip-shaped electrodes with an identical width, strip-shaped electrodes in the first and second electrode layers arranged alternately; a second substrate opposite to the first substrate with a liquid crystal layer therebetween; driving modules for driving the strip-shaped electrodes to form light shading parts and light transmission parts, one light shading part and one adjacent light transmission part defining a grating unit, at least one grating unit defining a grating part, the driving modules arranged in one-to-one correspondence with the grating parts; and a control module for generating driving signals in one-to-one correspondence with the driving modules according to a distance between the human eyes and the grating, thereby changing a width of the grating unit corresponding to a crosstalk position. A 3D display device and a grating driving method are provided.