The invention discloses a hydrogen peroxide decomposition inhibitor and a preparation method thereof. The hydrogen peroxide decomposition inhibitor is prepared from the following production materialsaccording to parts: 4 to 7 parts of sodium stannate, 3 to 9 parts of sodium pyrophosphate, 3.5 to 6 parts of sodium sulfide, 0.75 to 1.5 parts of zinc sulfate, 2.5 to 5 parts of sodium cyanide, 7 to 14 parts of potassium dichromate, 2 to 4 parts of potassium cyanide, 0.8 to 2 parts of carboxymethyl cellulose, 3 to 6 parts of diethanolamine, 4 to 8 parts of sodium metasilicate, 0.2 to 0.4 part of sodium oxalate, 0.15 to 0.3 part of methyl salicylate, 0.3 to 0.5 part of potassium benzoate, 0.4 to 0.6 part of sodium thioglycolate and 15 to 30 parts of modified ethyl ether. The hydrogen peroxide decomposition inhibitor provided by the invention can be used for effectively inhibiting decomposition reaction of hydrogen peroxide under a room-temperature or high-temperature condition; the raw material cost of the whole inhibitor is low; a processing method is simple and is worthy of being popularized.