Abstract: The research of the information dimension (D1) in an active fault zone considers the contribution of each seismic event to information and reflects the charact eristics of the temporal and spatial distributions of earthquakes from a new point of view, avoiding the shortcomings of the research about the fractal dimension of capacity (D0).The results of calcu ation show that the information dimension of the temporal distribution in the Xianshuihe active fault zone before the great Luhuo earthquake is D1 =0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions lof the temporal distribution of earthquakes about 17 years in the Anninghe active fault zone are respectively D1(tN) =0.1363 (for the north section )and A(ts) =0.06710 (for the south section ). The information dimensions of the spatial distribution are respectively D1(KN) = 1.053 (for the north section )and D1( Ks) = 0.7758 (for the south section ). The north section and the south section belong respectively to two self- similar systems with different information dimensions.The extent of the self- organization of seismic activity in the south section is higher than that in the north section. This is helpful for judging the major dangerous section in the key region of the seismic monitoring. The research about the information dimension of the temporal and spatial ditributions of earthquakes is significant for the exploration of active fault zones and seismisc prediction.