Based on the fractal viewpoint, the characteristics of different ranks and seasonal drought disasters sequences which is from 1368 to 1948  in middle  Gansu province are studied by using box counting algorithm. Then discuss the relation between temporal fractal dimensions and linear features indepth. Finally, the dynamic variation of the temporal fractal dimension is  analyzed. It is found that: ①Drought disaster is an objective fractal structure, the time series have self-organizing nature, drought disaster is self-organizing system;②The drought disaster lighter, the time fractal dimension bigger, the scaling range broader and the  time span oscillations shorter. ③The seasonal drought disaster′ temporal fractal dimension increases with the increasing of it is frequency; ④Mainly temporal fractal dimension of these sequences increases during the 581 years, and drought disasters tend to turbulence, the drought disaster system tends to balance and the stability drops. ⑤There is internal relationship between fractal analysis and conventional statistical methods.