The invention provides a preparation method for a hierarchical porous ZSM-5 molecular sieve. According to the preparation method for the hierarchical porous ZSM-5 molecular sieve, in a synthesis system of a silicon source, an aluminum source, an organic structure directing agent and deionized water, a proper amount of cationic surfactant cetyl trimethyl ammonium bromide is added to serve as a softtemplate agent, full stirring and uniform mixing are carried out so as to form molecular sieve synthesis sol-gel, then the sol-gel is dried so as to obtain dry glue, and then the hierarchical porousZSM-5 molecular sieve is prepared by using a dry glue conversion method. The preparation method for the hierarchical porous ZSM-5 molecular sieve has the advantages of being mild in preparation conditions, simple, convenient to use, high in efficiency, free of emission of synthetic waste liquid, environmentally friendly and capable of realizing industrial production, the good catalytic performanceis realized in the reaction of preparing the low-carbon olefins through catalytic cracking of n-octane, and therefore, remarkable environmental benefits and economic benefits can be achieved, and theindustrial production prospect is good.