In this paper, we discuss some nonlinear Poincare boundary value problems for nonlinear uniformly elliptic equations of second order in a multiply connected domain by using the methods of complex functions. At first we propose some modified boundary value problems for nonlinear elliptic systems of first order and give a priori estimates of solutions for the modified problems. Afterwards applying the above results, the continuity method and Schauder fixed-point theorem, we prove that the above nonlinear Poincaré problems with some conditions has a solution.