Based on the NS Model, a mixed traffic flow on single lane is simulated in the paper, which includes two-classification vehicles owing the different max-velocity, and a chaos recognition algorithm based on composite feature is advanced. How the traffic flow is changed for different density and different discrete degree and which channel is the right way to chaos is researched. And the influence of the density of traffic flow and the discrete of following-velocity on the chaos of traffic flow is analyzed in different values named approximate entropy and statistical complexity, which are changed as the mixed proportionality factor.