Network security situation prediction methods can make the security administrator better understand the network security situation and the network situation trend. However, the existing security situational prediction methods can not precisely reflect the variation of network future security situation caused by security elements' change and do not handle the impact of the interaction relationship between the various security elements of future network security situation. In view of this situation, a network situation prediction method based on spatial-time dimension analysis is presented. The proposed method extracts security elements from attacker, defender and network environment. We predict and analyze these elements from the time dimension in order to provide data for the situation calculation method. Using the predicted elements, the impact value caused by neighbor node's security situation elements is computed based on spatial data mining theory. In combination with node's degree of importance, the security situation value is obtained. To evaluate our methods, MIT Lincoln Lab's public dataset is used to conduct our experiments. The experiments results indicate that our method is suitable for a real network environment. Besides, our method is much more accurate than the ARMA model method.