The invention relates to a method for preparing diisopropylnaphthalene through a transalkylation reaction to mainly solve the problems of low naphthalene conversion rate, and severe carbon formation and fast inactivation of catalysts existing in the prior art. A catalyst used in the invention is organosilicon zeolite, the molar relation composition of the organosilicon zeolite is (1/n)Al2O3:SiO2:(m/n)R, wherein n is 10-350, m is 0.02-50, and R is at least one of an alkyl group, an alkenyl group or a phenyl group; and the Si<29> NMR solid nuclear magnetic atlas of the organosilicon zeolite includes at least one Si<29> nuclear magnetic resonance spectrum peak in a range of -80 ~ +50ppm; and the X-ray diffraction atlas of the organosilicon zeolite has d-spacing maximums in 13.2+/-0.2 angstroms, 12.3+/-0.1 angstroms, 10.9+/-0.3 angstroms, 9.1+/-0.3 angstroms, 6.8+/-0.2 angstroms, 6.1+/-0.2 angstroms, 5.6+/-0.2 angstroms, 4.4+/-0.3 angstroms, 4.0+/-0.3 angstroms, 3.6+/-0.2 angstroms, 3.4+/-0.1 angstroms and 3.3+/-0.2 angstroms. The method can be used in industrial production for preparing diisopropylnaphthalene.