The invention relates to a porous carbon piece, a preparation method of the carbon piece, and an application of the porous carbon piece in cigarette filters; dicyclopentadienyl iron and methyl chloride are added into a stainless steel high-pressure kettle to react at 300-600 DEG C for 30-90min, and then the porous carbon piece is obtained by cooling and washing; the prepared porous carbon piece is in the shape of a leaf with zigzag edge and can be used in cigarette filters. The preparation method is simple, is easy to control, suitable for industrial production and high in yield, and no rigorous reaction condition is needed, the prepared porous carbon piece is good in thermal stability, large in specific surface area and good in material absorbing performance; the harmful components such as phenols in the mainstream smoke are effectively reduced to more than 50%.