The invention belongs to the technical field of production of refractory materials and specifically relates to a preparation method of a microporous magnesium aluminate spinel raw material. The method comprises the following steps of: adopting magnesite and industrial aluminum hydroxide as raw materials, and performing grinding, shaping, firing and a series of processes to prepare a product. The microporous magnesium aluminate spinel raw material prepared by the preparation method disclosed by the invention can be used as the raw material for high-strength and low-conductivity magnesium aluminate spinel refractory material products and heat insulation unshaped refractory materials with the using temperature above 1580 DEG C.