The present invention provides a device and method for realizing prefix code construction. The device includes a sort indexer, a generator and a sequence regulator. The sort indexer is used to sort a group of received code lengths to obtain a group of sorted code lengths, and record the position correspondence relationship. The generator receives the sorted code lengths and orderly generates the prefix codes. Except that the first prefix code is preconfigured, the generator generates a current prefix code by adding one to the adjacently previous prefix code and then shifting left by a certain number of bits. The sequence regulator is used to receive the prefix codes corresponding to the sorted code lengths, and regulates the sequence of the prefix codes corresponding to the sorted code lengths according to the position correspondence relationship recorded by the sort indexer to obtain the prefix codes corresponding to the code lengths.