The shape‐defined ZnFe2O4 spinel with cubic and octahedral morphology were hydrothermally synthesized, respectively, and used as catalyst precursor for Fischer‐Tropsch synthesis (FTS). The structure of ZnFe2O4 spinel was changed to ZnO and Fe5C2 (Fe5C2/ZnO) after reduction and carbonization. Interestingly, ZnFe2O4 with cubic morphology exhibited much higher catalytic activity and selectivity toward low‐carbon olefins (C2‐C4) than the octahedral one under identical conditions, and the latter tended to produce the saturated alkanes. The primary properties for ZnFe2O4 materials before and after reduction were systematically studied through a series of characteristic technologies to reveal the difference in catalytic performance between the two ZnFe2O4 spinel with different morphology.