A silicon etching method of etching a silicon substrate to form silicon trenches having different width dimensions includes: S1, providing a silicon substrate; S2, depositing a mask layer on the silicon substrate; S3, corroding the mask layer to form windows having different width dimensions, wherein a mask layer having a certain thickness is reserved at least at a bottom portion of a window having a non-minimum width dimension, such that all the silicon trenches have the same depth after step S4; and S4, corroding the mask layer at the bottom portion of the window and the silicon substrate to form the silicon trenches. The mask layer having a certain thickness is reserved at the bottom portion of the window having the non-minimum width dimension, a relatively large window is protected, and a relatively small window is etched first, so that the finally obtained silicon trenches have the same depth.