Chaos dynamic behavior of dense phase pneumatic convey system is analyzed in the paper. The maximum Lyapunov exponent and correlation dimension of time series of concentration signals of pulverous coal are calculated. The results show that the maximum Lyapunov exponent of the system is greater than zero. This indicates the system is chaos. From dense moving flow to settling flow, chaotic attractor gradually diminishes, correlation dimension decreases from 1.535 9 to 1.076 4. It shows that from dense moving flow to settling flow, the system chaotic degree gradually weakens.