The invention provides a preparing method of 2,6,11,15-tetramethyl 2,4,6,8,10,12,14 hexadecene heptaene dialdehyde. The preparing method comprises the first step of using 1,2-dihalogenated ethane as a raw material, making 1,2-dihalogenated ethane react with triethyl phosphite under the effect of a catalyst through Michaelis-Arbuzov to obtain tetraethyl ethylenebisphosphonate; the second step of making phosphonate react with pyruvic aldehyde dimethyl acetal under an alkali effect and through Horner-Wadsworth-Emmons to obtain 3-methyl-4,4-dimethoxy-2-butylene-1-diethyl phosphate; the third step of making 3-methyl-4,4-dimethoxy-2-butylene-1-diethyl phosphate directly react with 2,7-dimethyl-2,4,6-octatriene-1,8-dialdehyde through a 'one pot method' without separation to obtain 2,6,11,15-tetramethyl-2,4,6,8,10,12,14-hexadecene heptaene dialdol methanol; the fourth step of making the acetal compound be subjected to hydrolysis protection under an acid condition to obtain the target compound 2,6,11,15-tetramethyl 2,4,6,8,10,12,14 hexadecene heptaene dialdehyde. According to the 'one pot method' processing technology, the raw materials are easy to obtain, and the preparing method is simple and coherent, simple in operation, mild in condition, good in yield, less in three wastes, and is thus suitable for industrialized production.