Nowadays most of the widely used compressions encoding methods are implemented by using the Huffman tree.There are many operational processes around the Huffman tree.One variable-length optimal encoding method is proposed to simplify the encoding process.The optimal code length can be get from the probability compensation process.The final coding can be determined without the Huffman tree after knowing the code length and probability

and the result meets the challenge of the variable-length optimal coding theorem and the prefix code.After testing

the method is proved to be able to get the variable-length optimal coding quickly and effectively.The calculation and stored procedures are simplified.