Disclosed is a brain cognitive state judgment method based on a non-negative 
tensor projection operator 
decomposition algorithm. The method includes the steps of S1, collecting brain 
functional magnetic resonance images under different cognitive tasks to form a data sample set, carrying out preprocessing, and forming a sample set according to 
tensor modes, wherein the sample set is divided into a 
training set and a testing set according to the cognitive tasks, and the 
training set comprises functional magnetic 
resonance data in similar proportion of different cognitive states, S2, computing non-negative 
tensor projection operator 
decomposition of the training sample set to solve out a non-negative 
feature transformation matrix, projecting training samples to a non-negative tensor feature sub-space for 
dimensionality reduction to obtain a non-negative feature tensor set of the 
training set, S3, using lower-dimension non-negative feature tensor data after 
dimensionality reduction as input of an STM for training to solve out the optimum 
projection direction of the STM, and S4, projecting brain functional magnetic 
resonance data of tested samples to the non-negative tensor feature sub-space obtained through training to obtain non-negative feature tensors of the brain functional magnetic 
resonance data in the sub-space, and inputting the non-negative feature tensors of the tested samples to the trained STM to judge cognitive state types of the non-negative feature tensors.