The invention relates to a flexible microgripper through topological optimization, which belongs to a microactuators in the technical field of the micro electro mechanical systems and is a flexible electrothermally driven microgripper. The flexible microgripper consists of a shift amplifying section and a driving section and is an integral structure with the eudipleural gripper body. The shift amplifying section M is designed by using the topological optimization method and comprises left and right triangular components and a flexible rod, wherein the left and right triangular components randomly hollow triangle structures. The driving section comprises a V-shaped beam array, left and right driving fixed rods and left and right electrodes. The microgripper has the advantages of unique and novel structure, large output shift, rapid response, simple control, convenient integration and is effective and energy-saving without applying drive in the process of gripping objects, thereby the microgripper is quite suitable for gripping minute objects for micro-assembly, micro-operation and the like.