Using off-resonance Raman scattering at room temperature, we have observed, for the firsttime, the confined longitudinal optical (LO) phonon modes in ZnSe layer of the ZnSe-ZnTe strined layer superlattice(SLS) which have the lattice mismatch as large as 7.3%. The red shifts of LO phonon frequencies induced by confinement and the shifts induced by the elastic strains have been calculated. The latter are much larger than that induced by former. The blue shifts induced by tensile strain in ZnSe layer and that red shifts induced by comperssive strain in ZnTe layer made some confined LO modes in two individual layers overlap. Therefore, the folded LO mode had been observed in ZnSe-ZnTe SLS.