Abstract We study the effects of phonon interaction on the superconducting pairing in the high Tc superconductors (HTSC). Using coupled BCS gap equations, we found that phonon interaction can induce a s-wave component to the d-wave gap, mediated by Antiferromagnetic (AFM) spin fluctuations, in the (D+iS) form. However, Tc is not enhanced compared to the pure d-wave pairing without phonon interaction. On the other hand, anisotropic phonon interaction can dramatically enhance the d-wave pairing and Tc itself, together with the AFM spin fluctuation interaction. This (DAFM+ Dph) type pairing exhibits strongly reduced isotope coefficient despite the large enhancement of Tc by phonon interaction. Keywords : High Tc Superconductor, Pairing Mechanism, Phonons