A bloom filter and an implementation method thereof are provided. The implementation method has a ternary rule encoded as a rule binary codeword according to a predetermined encoding rule; has a packet encoded as at least one packet binary codeword according to the predetermined encoding rule; and comparing the rule binary codeword and the at least one packet binary codeword to decide a following processing of the packet. The predetermined encoding rule includes: tagging 0 or 1 into most significant bit (MSB) of the output binary codeword based on mask length of the input codeword; placing the prefix of the input codeword right after MSB of the output binary codeword; and tagging a string to last bits of the output binary codeword based on the mask length, and the bit number of the string equals to the mask length.