Prepared method of modified activated carbon

The invention relates to a preparation method used for a PSA (pressure swing adsorption) process adsorbent. In the production of polysilicon, a great deal of tail gases is purged, and a PSA method is a good method for separating and recovering the tail gases. The adsorbent is modified activated carbon which is subjected to special processing, resistant of high temperature, free of dust drop, suitable for separating and recycling the tail gases and capable of obtaining a polysilicon product with high quality.