Content addressable memory and similarity matching method

The invention provides a content addressable memory which comprises a CAM (Central Address Memory) array, a matching rate maximizing unit, a matching line read circuit and an address encoder, wherein tail lines of all CAM units in one same row of the CAM array are connected with the matching rate maximizing unit; the matching rate maximizing unit is used for outputting a row of the CAM units, with the minimum tail circuit current, of the CAM array as a first level signal, and used for outputting other rows as a second level signal; the matching line read circuit is used for respectively adjusting the first level signal and the second level signal and subsequently outputting the adjusted first level signal and second level signal; the address encoder is used for outputting a storage address corresponding to the adjusted first level signal as a storage address of a data word with the highest similarity. The invention further provides a corresponding similarity matching method. By adopting the content addressable memory, not only is the maximum matching rate operation of the data word achieved, but also compared with a voltage type maximizing circuit, the content addressable memory is high in comparison speed and small in influence on overall CAM speed.