This paper presents more realistic models,including the microscopic ones and the macroscopic ones, based on the synthetical analysis of the existing ones. Specifically, we present a full velocity difference(FVD) car-following model, a cellular automata(CA)model that considers the velocity effect of the preceding car, another CA model that can describe the synchronized flow, and a speed gradient (SG) macroscopic model which can describe the anisotropic properties of traffic flow. The various nonlinear phenomena in traffic flow are investigated through theoretical nanlyses and numerical simulations, and the relationship between different kinds of models are discussed.