[en] We study the longitudinal polarization of hyperons and antihyperons at forward pseudorapidity, 2.5<η<4, in singly polarized pp collisions at Relativistic Heavy Ion Collider energies by using different parametrizations of the polarized parton densities and different models for the polarized fragmentation functions. The results show that the Σ⁺ polarization is able to distinguish different pictures on spin transfer in high energy fragmentation processes; and the polarization of Λ and Λ hyperons can provide sensitivity to the helicity distribution of strange sea quarks. The influence from beam remnant to hyperon polarization in the forward region is also discussed.