A web system license based on multi-way tree search includes steps of: identifying a requiring URL of each function; using the requiring URL of the function as a mark, writing the mark in a license; encrypting the license for generating a cipher text, and storing the cipher text in a web system; during initializing of the web system, decrypting the cipher text and sending to a memory; establishing a multi-way tree according to a URL of an authorized function in the license; and receiving a requirement for a specific function by the web system, using the requiring URL as a searching value and matching in the multi-way tree; wherein if a corresponding URL is found, the function is authorized and further operation is required until response returning; if the corresponding URL is not found, the requirement is intercepted, and a response is returned.