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 reverse side of the silicon wafer prepared in the step 1 is thinned; 3, variation in thickness of the silicon wafer and pressure change in the thinning process of the step 2 is recorded; 4, the etching depth uniformity of the deep trenches is calculated according to the variation in thickness and pressure change plotting curve of the step 3. 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.