Using the full-potential linearized augmented plane wave method based on the density functional theory, spin-polarized calculations of electronic structure for the zinc-blende CrS and CrSe are performed. Zinc-blende CrS and CrSe at their respective equilibrium lattice constants are half-metallic with the same total magnetic moment of 4.00B. The electronic structures of zinc-blende CrS and CrSe are calculated under uniform strains from -10% to +10% relative to the equilibrium lattice constant. The calculated results indicate that zinc-blende CrS and CrSe can maintain half-metallic ferromagnetism and keep the same total magnetic moment of 4.00B from -1% to 10% and from -4% to 10% uniform strain, respectively.