Microstructure, martensitic transformation temperature and shape memory effect of Co-Fe alloys were investigated by optical observation, X-ray diffraction, DSC and bending tests. Results show that the shape memory effect of Co-Fe alloys is associated with the fcc/hcp martensitic transformation. When Fe content is higher than 5.65wt%, the microstructure exhibits single γ phase with fcc structure. When Fe content is lower than 5.6wt%, the microstructure consists of γ phase and ε martensitic phase with hcp structure. The martensitic transformation temperatures of Co-xFe alloys are almost linearly decreased with increasing Fe content, following the relationship: Ms (℃) = 417-69.97x(Fe%). The highest recoverable strain of Co-4Fe (wt%) alloy is 0.86%. It is believed that Co-Fe alloys will exhibit better shape memory effect after proper heat treatment and shape memory training