Abstract: Complex fluids and biological polymers, such as solution of proteins or DNA, have very rugged potential energy surface in their conformational spaces. The simulations of equilibrium properties and dynamical behaviors in these systems are usually difficult due to too long required simulation time. We develop some simulation techniques, such as temperature walking on continuous paths, re-weighting ensemble dynamics simulations, for enhanced sampling in these systems. A direct network representation in high-dimensional conformational space, based on meta-stable states and interstate transitions, is also presented to accelerate the molecular dynamics simulations and to understand results of simulations. We illustrate the application of the techniques in Lattice spin models, Lennard-Jones fluids, and polypeptide.