Using powder metallurgy sintered billet as raw material, Mo-47.5Re (wt%) foils with the thicknesses of 0.035 and 0.030 mm were obtained by multi-pass rolling and intermediate annealing. After hydrogen annealing at 1300–1900 °C, metallurgical microscopy, SEM and EDS were used to analyze the effect of annealing temperature on characteristics of σ-phase. EDS analysis indicates that Mo:Re atomic ratio of second phase in the ND direction approaches to 1:1, and that in the RD direction is close to or lower than 1:2, so the majority of second phase in Mo-47.5Re foils is σ-phase; but Mo:Re atomic ratio of second phase in the RD direction is relatively low, even reaching 1:4. The micrograph characteristics of Mo-47.5Re foil includes large grains, few deformation twins, and larger and more σ-phase particles in grains than at the grain boundary. The number of σ-phase in 0.035 and 0.030 mm thick foils increases first and then decreases with rasing annealing temperature. After annealing at 1300 °C, σ-phase number of 0.035-mm- sample reaches the maximum and the grain size is significantly reduced, while 0.030-mm-sample shows this phenomenon at 1500 °C. After annealing at 1900 °C, a few small-sized σ-phase particles remain in the RD direction of 0.030-mm-sample, and all σ-phase particles in the ND direction of 0.030-mm-sample and those in RD and ND directions of 0.035-mm-sample are totally redissolved and disappear. In as-rolled and relatively low-temperature annealed samples, such as 1300 °C, most σ-phase particles have irregular polygonal morphology, and a few of them are spherical. After annealing at 1500 °C and higher temperatures, σ-phase particles in some samples exhibit a cube shape.