Atomic oxygen is one of the most important environmental element impacting spacecraft performance in LEO space environment. Materials used on the surface of the spacecraft may be eroded away through the reaction of Atomic oxygen, which also causes damage to spacecraft components, seriously reducing the spacecraft's orbit life. In order to avoid over-protection, This paper proposes an atomic oxygen simulation method to calculate atomic oxygen cumulative flux of different surface on spacecraft, which considered the flight attitude and mutual occlusion effect of the spacecraft. The deviation of the simulation result from the measured data of NASA is negligible. The simulation method can be used for atomic oxygen protection design of low orbit spacecraft.