The invention relates to a hierarchical porous SAPO-34 molecular sieve and application thereof in a methanol-to-olefin (MTO) reaction. The hierarchical porous SAPO-34 molecular sieve is prepared by amethod comprising the following steps: 1) uniformly mixing an aluminum source, a phosphorus source, a silicon source and a templating agent in water, and preparing synthetic gel; 2) introducing polyacrylamide to the synthetic gel, and preparing mixed gel; and 3) performing hydrothermal crystallization treatment on the mixed gel, and roasting to obtain the hierarchical porous SAPO-34 molecular sieve. According to the provided hierarchical porous SAPO-34 molecular sieve, through introducing the polyacrylamide to the initial gel, the SAPO-34 molecular sieve with a hierarchical porous structure isprepared after the hydrothermal crystallization and roasting treatment. The SAPO-34 molecular sieve is abundant in porous structure, the catalytic life in the MTO reaction and the low-carbon olefin selectivity are improved, and the SAPO-34 molecular sieve expresses the more excellent MTO catalytic performance.