The invention discloses a gas supply device and method for multi-working-medium gas micro-flow calibration. According to the gas supply device, a gas storage system formed by connecting a plurality of high-pressure gas bottles in parallel is used for providing multiple calibration gases, and the calibration gases conforming to the working medium actual gas can be provided. Through an electrical path converter and a pressure stabilizing system, the inlet and outlet pressure of the calibration gases is ensured, the pressure of the provided calibration gases is consistent with the actual pressure of the working medium gas, the actual work condition is better met, and working medium gas micro-flow calibration is more accurate. By means of the gas supply device and method, the calibration gases conforming to the working medium actual gas can be provided, and meanwhile the pressure of the provided calibration gases is consistent with the actual pressure of the working medium gas; and the gas supply method is simple, feasible and easy to operate.