The invention discloses a method for monitoring the corrosion depth of silicon in real time, belonging to the technical field of micro-electronics mechanical system processes. The method comprises the following steps of: simultaneously corroding a silicon-corroding slice and an auxiliary silicon slice for monitoring the corrosion depth of the silicon-corroding slice under the same condition, wherein the auxiliary silicon slice comprises a corrosion groove, a corrosion surface and a monitoring surface, the corrosion groove is positioned on the surface of the auxiliary silicon slice, the corrosion surface is positioned at the bottom of the corrosion groove, the monitoring surface is positioned on the side surface of the corrosion groove, the corrosion surface and the monitoring surface haveidentical crystal orientations, and corrosive liquid is contained in the corrosion groove; and immersing the corrosion surface, the monitoring surface and a monitoring line formed by crossing the monitoring surface and the surface in the corrosive liquid, and then determining the corrosion depth by using the displacement of the monitoring line in a corrosion process or after the corrosion process. The method can be used for the micro-electronics mechanical system processes.