Identification of crystal concentration and evolutional temperature in minerals helps study evolutional rules of minerals and mining and development of mineral resources. This paper uses evaporation crystallization to make NaCl and KCl samples in different proportion, which are used to simulate the mixed crystal under different percentages and temperatures. Samples are then tested by terahertz time-domain spectroscopy. The refractive index and absorption coefficient of the mixed crystals at the same growing temperature rise linearly with a rising NaCl percentage, and that of the mixed crystals with same proportion shows a sinusoidal curve as growing temperature rises, which reveals that terahertz time domain spectroscopy can mark the components percentage and growing temperature of the mixed crystal at the same time. This research offers a new tool to study evolutional rule of mineral crystals and to mine and develop mineral resources.