This paper decribles a kind of thermo-optic coefficients measuring instrument which can be used for exact measurement of five coefficients of optical materials. A new design shich combining two kinds of interferometers, computer control and data processing and adoped, resulting in a high-precision measurement. An accuracy of ± 3 × 10-7℃-1 has been achieved in measuring the thermal expansion coefficient α in a low temperature region, temperature coefficient of refractive Index β and thermo-optic coefficient of refractive Index β and tiiermo-optic coefficient ω.