Magnesium chloride hex-ammoniate (MgCl(2) center dot 6NH(3)) is an intermediate to produce anhydrous magnesium chloride (MgCl(2)) by method of reaction crystallization. MgCl(2)-6NH(3) is decomposed at 670K to produce anhydrous magnesium chloride. The process of thermal decomposition and its non-isothermal kinetics Of MgCl(2) center dot 6NH(3) is studied. Results show that the thermal decomposition process is made up of three stages, the thermal decomposition functions and the thermal decomposition kinetics parameters, such as activation energy (E), pro-exponential factor (A) of MgCl(2) center dot 6NH(3) for each step are obtained by means of the Acher differential, the Coats-Redfiern integral and multi-accelerated heating rate method. This study provides a valuable theoretical basis for MgCl(2) center dot 6NH(3) decomposition process on industrialization.