The present invention relates to wax dielectric for heating temperature control valve and its preparation process. The destination product is prepared with fluid wax, wax paste, soap wax, etc containing C9-C20 components and through decompression distillation in 5-20 deg.c fraction width, sweating of the fractions in the smelting point temperature as the ultimate temperature, equal weight ratio mixing, refining and other technological steps. The product may be used in heating temperature controlling valve for temperature control in 5-30 deg.c and has basically the same stroke each degree of temperature. The product may be also used in other automatic temperature controlling devices.