The invention discloses a method for detecting the depth of an etched groove through the current change. A special detection region is designed, so that the depth of the etched groove is reflected in real time. The detection region is prepared through the MEMS processing technique and signals are read through a current meter. According to the method, a function region and the detection region are well isolated electrically through an SOI silicon wafer and the MEMS processing technique and the function region is prevented from being damaged through detection current. Meanwhile, through pattern transfer, etched windows of the function region are copied in the detection region and it is guaranteed that the etching conditions of the detection region tend to be identical to those of the function region. Strict electricity modeling calculation is conducted on the deep groove structure of the detection region, the relation between the etching depth and current signals is acquired, and on the basis, the depth of the etched groove is monitored in real time through detection of the current meter.