The invention belongs to the technical field of electroencephalogram recognition, and particularly relates to a time-varying brain network reconstruction method facing dynamic video target detection. The method comprises the following steps that a scalp electroencephalogram signal of a testee under an acquired dynamic video is mapped to a cortex space, and a cortex signal with high temporal-spatial resolution is reconstructed; and an interested brain area is selected from the cortex space to serve as a network analysis node, and a cortex time-varying brain network connection graph reflecting the cognitive processing process is obtained by analyzing the neural information processing process from target search to target discovery according to cortex signal. According to the method, a neural processing mechanism of the process from search to discovery of a dynamic visual target is expanded, scalp electroencephalogram with the high temporal-spatial resolution is selected to be mapped into cortex electroencephalogram with the high temporal-spatial resolution, a finer brain activity diagram can be obtained, the brain neural information processing process is further explored through a time-varying network analysis method, the application of a brain-computer interface in an actual environment is facilitated, and the application prospect is good.