Abstract: The three parallel algorithms for nonlinear dynamic analysis of large structures are presented using domain decomposition and preconditioned conjugate gradient (PCG) technique. In the first formulation called the global interface formulation, the PCG algorithm is applied on the assembled interface stiffness coefficient matrices of all subdomains. In the second formulation called local interface formulation, the PCG algorithm is formulated using the unassembled local Schur complement matrices of subdomains, where incomplete Cholesky preconditioner is employed. The third formulation called local subdomain formulation operates on the local unassembled subdomain matrices and the preconditioner is constructed using the local subdomain information. Newmark-β average acceleration technique is employed for time integration. A parallel program is developed with message passing interface as software development environment. Numerical example is implemented to validate as well as to evaluate the performance of the three proposed PCG formulations. Numerical studies indicate that the proposed parallel PCG formulations are superior in performance when compared to the conventional domain decomposition algorithms with parallel direct solver.