A parallel finite element solver is developed for simulation of the unsteady incompressible viscous flows. Implicit mid-point scheme is used to discretize time variable. Based on unstructured grid, velocity and pressure are discretized by classical P2-P1 Taylor-Hood mixed finite element. Resulting linear algebraic systems are large-scale, sparse, non-symmetric and ill-conditioned. Using a specially designed iterative strategy, it is solved by preconditioned GMRES method with modified pressure-convection-diffusion(PCD) preconditioner. A number of numerical experiments verify scability and validity of the solver. Especially, driven cavity flow simulation in 3D (Re=3200.0) clearly shows existence of primary eddy, downstream secondary eddy, upstream secondary eddy, end-wall vortices and T-G-like vortices. A parallel efficiency comparison with least-squares commutator(LSC) preconditioner is also given.