MSC:Keywords: Riemannian manifolds Fully nonlinear parabolic equations First initial-boundary value problem a priori estimates a b s t r a c tIn this paper, we are concerned with the first initial-boundary value problem for a class of fully nonlinear parabolic equations on Riemannian manifolds. As usual, the establishment of the a priori C 2 estimates is our main part. Based on these estimates, the existence of classical solutions is proved under conditions which are nearly optimal.