The creep behavior of equiaxed, duplex and widmanstatten structures of Ti6321 alloy under tensile stress of 706MPa for 200h was studied. The microstructure morphology of the samples after creep was observed by metallographic microscope and transmission electron microscope (TEM), and the dislocation slip types of different microstructures of Ti6321 alloy were analyzed by trace method. The results show that the creep strain of equiaxed structure of Ti6321 alloy is the largest, followed by duplex structure and widmanstatten structure. Through the first derivative of creep curve, the turning point of creep rate change was found, and the creep strain of different stages was obtained. It is found that the primary creep strain is positively related to the amount of residual dislocation in the structure. The creep mechanism of Ti6321 alloy at room temperature is mainly dislocation slip, the original cellular dislocation decomposes and the new dislocation slip forms during the tensile process of equiaxed structure, the new dislocation is (10-11)<11-23> cross slip; the primary α phase of duplex structure mainly occurs {10-10}<11-20> prismatic slip, the secondary α phase occurs (-1101)<-2110> pyramidal slip; widmanstatten structure starts (0001)<-2110> basal slip and (10-11)<10-12> pyramidal slip.