Institute of Crystal Materials and State Key Laboratory of Crystal Materials, Shandong University, Ji an 250100(Received 18 March 2000)The data of the thermal expansion and specific heat of cadmium mercury thiocyanate crystal have been obtained.The specific heat is 0.7588J/g℃ at room temperature. The thermal expansion occurs in the direction parallel to the c-axis, and the thermal contraction occurs in the direction parallel to the a-axis. The thermal expansion is the same as the thermal contraction at 353 K. The relationship between thermal properties and crystal structure is discussed.