Abstract: In order to analyze fractal characteristic of traffic-flow time series，multifractal spectrum of real traffic-volume time series is calculated.The result shows that left endpoint is higher than right endpoint，and vertex is in left side.It can be explained number of highest volume condition is larger than that of smallest.Compared with multifractal spectrum of traffic time series which have different statistic gaps，the gap is wider，and the width of spectrum is wider，but deviation remains larger than zero，so the traffic-volume time series which has large statistic scale has more multifractal characteristic and irregularity.