In this paper, chaos in fractional-order neutral delay differential equation (NDDE) is discussed. Chaos in the system is illustrated by presenting its waveform graphs, states diagrams and largest Lyapunov exponent. The largest Lyapunov exponent (LLE) and the LLE of the system with different parameters are derived. In addition, we compare the fractional-order with integer NDD systems, and find that the convergence speed of the synchronization fraction system is faster. We also get the conclusion that the fractional NND system has better anti-interference ability.