Quartz glass is widely used in optical instruments of aerospace,medical exploration,optical imaging and its optical performance is one of the key factors that must be considered in the design of the instrument.The thermo-optical coefficient is an important optical performance parameter,and its change will affect the imaging quality and detection accuracy of the optical element.Therefore,the accurate measurement of the quartz glass thermo-optical coefficient is necessary for the design and calibration of the instrument.In this paper,a single-mode passive silica fiber is used as the measurement object,and a method for measuring the thermo-optical coefficient of quartz glass based on the all-fiber laser self-mixing interference technology is proposed.In the experiment,pure silica single-mode fiber is used as the external cavity of the interference system and fused with the fiber laser to form an all-fiber enclosed laser self-mixing interference thermo-optic coefficient measurement system.A fixed temperature range is given by the high-temperature heating box,and the thermo-optical coefficient of the quartz glass is calculated by the interference fringe counting method.The experimental results show that the resolution of the system to the thermo-optical coefficient can reach 1.632 9×10－7/(0.1 ℃).This research result lays a foundation for further research on the measurement of the thermo-optical coefficient of quartz glass and the application of fiber laser self-mixing interference.