In this work, byemploying the Leggett-Williams fixed point theorem, we study theexistence of at least three positive solutions of boundary valueproblems for system of third-order ordinary differential equationswith -Laplacianbegin{eqnarray*}left { begin{array}{ll} (phi_{p_i}(u_i''(t)))' + a_i(t) f_i(t,u_1(t), u_2(t), ldots, u_n(t)) =0 hspace{1cm} 0 leq t leq 1, alpha_i u_i(0) - beta_i u_i'(0) = mu_{i1} u_i(xi_i),hspace{0.2cm} gamma_i u_i(1) + delta_i u_i'(1) = mu_{i2} u_i(eta_i), hspace{0.5cm} u_i''(0) = 0,end{array} right.end{eqnarray*}where , are -Laplacianoperators, and for .
