In this paper, high temperature resistance of basalt fibers with different SiO2 and Al2O3 contents was studied. The thermal expansion coefficient, crystallization performance and high temperature viscosity of basalt glasses was analyzed by TMA (thermomechanical analyzer), STA (synchronous thermal analyzer) and high temperature viscometer. The results showed that the monofilament strength, monofilament strength retention and high temperature viscosity of the basalt fibers increased with the increasing content of SiO2 and Al2O3, and the thermal expansion coefficient of basalt glass reduced and the thermal stability of the basalt fiber was improved. However, when the total content of SiO2 and Al2O3 was more than 78%, the melting temperature of basalt ore became higher, which will reduce the service life of platinum bushing and refractory material.