Basic magnesium chloride whiskers were prepared with saltworks brine and Sodium Hydroxide as starting raw. Morphology and crystal Structure of products were investigated by SEM and SAED. The whiskers were single crystal material with the average Diameter of 0.5-1μm and length of more than 150μm. Crystalline structure of the samples were characterized by XRD, and product is 9Mg(OH)2?MgCl2?5H2O. It’s functional groups of different magnesium ion concentration were investigated by FT-IR. Magnesium oxide whiskers were program calcinated high temperature at heating rate of 2-5℃/min, Keeping the morphology and single crystal structure of magnesium oxide whiskers well. The possible mechanism of thermal decomposition process was speculated also.