The invention discloses a method for monitoring etching depth uniformity of deep trenches. The method comprises the following steps that 1, a through silicon via silicon wafer is prepared; 2, the silicon wafer is thinned on the thinning machine, stopping after detecting the end point, thickness value of the silicon wafer is measured at the moment; 3, a coordinate of a measuring point in the silicon wafer is determined; 4, wet etching is conducted on the measuring point, whether or not through hole in the measuring point is exposed is observed under a microscope; 5, the wet etching is conducted stepwise, when all the through holes are exposed, the thickness value of the silicon wafer is recorded at this time, the etching depth uniformity of the deep trenches is calculated according to the recorded wafer thickness value. The method has the advantages of simple operation process and low cost, and can effectively monitor the etching depth uniformity of the deep trenches, the method is not affected by the depth of the deep trenches, especially for the deep trench process that both sides of a conventional infrared machine adopted are hard to detect the large depth-to-width ratio in the prior art, and the method can also achieve the good monitoring effect.