In this paper, the process of the ablation of meteoroid which radius is less than 100 μm is analyzed by adopting a continuous evaporation model of micro meteoroid, and the impact on the metallic layer in mesosphere （80～110 km） is estimated. The observation of radio meteor radar and Lidar suggests that the ablation of meteoroid which radius is lager than 100 μm is not the major source for metallic layer. From momentum equation and energy equation, the ablation profile of meteoroid with different radius in different velocity is calculated, and the variation of the ablating cut-off height is analyzed. According to the long term observation of lidar, it is concluded that the flux of meteoroid with the radius of 10～40 μm is the major impact of the normal metallic layer. Meteoroids with radius larger than 100μm and average velocity of 12km/s ablate around 80km which is lower than peak of the normal metallic layer. The micro meteoroids with different velocity will result in similar ablation cut-off height if they don＇t ablate completely. Meteoroids with radius of 10～40 μm and injection velocity of 14 km/s ablate mainly at the altitude of 80～110 km and their ablation cut-off heights are also near the underside height of the metallic layers.
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