An RC oscillator is provided for improving stability of oscillation frequency. The circuit includes an input module, an oscillating module, an inverting module, first and second compensating modules and an output module, wherein the input module provides two-path charging currents and bias current for the oscillating module; the oscillating module outputs a first high level or a first low level to the inverting module under the control of the two-path charging currents and bias current, and improves frequency tuning accuracy of the oscillator; the inverting module inverts the first high level to a second low level or inverts the first low level to a second high level, and outputs the second low level or the second high level to the output module; the output module outputs the second high level and the second low level; and the first and second compensating modules improve stability of the oscillation frequency.