The Monte Carlo method is applied to simulate solar X-ray bursts (1-8 Å, 0.5-4 Å) transportation in earth's atmosphere. And the electron production rate due to solar X-ray bursts penetrating in ionospheric D-layer is calculated. From that, we can get the value of cosmic noise absorption. Aexample result of solar X-ray bursts is compared with the value of Riometer absorption observed in antarctic Zhong-Shan station, showing very good correlation.