Objective The variation of etching rate in micro-etching on the die steel was studied. Methods Spray etching was used in etching the surface of the die steel with mask processing. The impact of the mask gap width, spray pressure and etchant temperature on the etching rate was investigated. Results The etching rate increased with the increasing mask gap width, when the mask gap was wider than 150 μm, the etching rate increased rapidly. Larger spray pressure was benefit for updating the etchant and excluding the etching product, when the reaction was sufficient, the etching rate increased. When the etchant temperature elevated within a certain range, the etchant activity increased, so as the etching efficiency and the etching rate. Conclusion The optimal condition was a mask gap width of 150 ~ 200 μm, a spray pressure of 1. 0 ~ 1. 4 MPa, amd an etchant temperature of 35 ~ 40 ℃ . Under this condition, the etching rate and the processing efficiency were both high. Meanwhile, it helped to ensure a higher dimensional accuracy.