Abstract: To study the new type of dosimeter with a dose up to the ultra-high dose range of MGy, the electron spin resonance (ESR) method is used to measure the signal intensity of the sample irradiated by gamma rays or electron beams. Preliminary studies have been carried out through the selection of sensitive materials, linearity after irradiation, and stability. The results showed that the quartz can be used as a raw material for ultra-high dosimeters. After 15 min 300 ℃ proper heat treatment, the signal intensity of the irradiated quartz sample can maintain good stability within one year with a change of less than 3%. The radiation dose and the E′ signal intensity of quartz are proportional to the dose range of 10-10³ kGy. The fitting coefficient is above 0.99. Compared with the high-purity quartz sample without heat treatment, the stability and R² of fitting function of quartz sample are significantly improved. Therefore, the quartz dosimeter is suitable as a working dosimeter in the ultra-high dose range.