The invention relates to a preparing method for a finned inner cooling structure cooling pipe based on gel electrochemical machining. The method specifically comprises the steps that preprocessing is carried out, and internal pipe flaw detecting and surface cleaning are carried out; the activating treatment should be carried out after inert metal is cleaned; a machining stage mainly comprises device platform establishing and an electrochemical machining stage, manual machining and automatic machining can be selected in the machining process in a self-service mode, and the machining efficiency is improved; a postprocessing stage mainly comprises checking and post cleaning, and purified clean water is used for performing cleaning during the experiment. The gel electrolyte comprising NaNO3 is planned to be utilized for being prepared into a rib shape, an electrode is selectively wrapped and machined to serve as a negative electrode, a machining piece serves as a positive electrode, and electrochemical machining is carried out. The preparing method is particularly suitable for machining of a finned inner cooling structure of the inner wall of a traditional pipeline, whether gel electrolyte is in contact or not can be controlled in a reaction area other structures of the pipeline cannot be affected, a finned cooling structure of the inner wall of the pipeline is achieved, and the cooling performance of a scattering channel is improved.