Abstract: Desensitization of emulsion explosives was quantified by means of measuring its explosion shock waves in water, and a concept of desensitization degree was used to express the extent of desensitization which could compare and analyze the anti-pressing performance of explosives quantitatively.The relationship of Span-80 content to pressure desensitization of emulsion explosives was studied with the method.Emulsifier content showed strong influence on pressure desensitization of emulsion explosives and desensitization degree decreased with the increase of Span-80 content.While the Span-80 content reached 4%, the desensitization degree became the least.The anti-pressing performance of the explosive was the best, but the anti-pressing performance would decrease if the Span-80 content further increased.