The invention relates to a green method for preparing an SBA-15 mesoporous molecular sieve, and belongs to the technical field of mesoporous molecular sieve synthesis, in particular to a method for synthesizing the SBA-15 mesoporous molecular sieve under the condition of no additional addition of acid and alkali through adding one kind of additive into a synthesis system. According to the method, a poly oxirane-poly epoxy propylene-poly oxene triblock copolymer high molecular surfactant is used a template agent; ethyl orthosilicate is used as a silicon source. Compared with a conventional method, the green method has the advantages that only few additives need to be added; the SBA-15 mesoporous molecular sieve with high crystallinity degree can be synthesized under the condition of no additional addition of acid and alkali through adding few additives; the process is simple and convenient; the cost is low; the wide industrial application prospects are realized.