The invention discloses a system error locating method and apparatus. The method comprises the steps of setting an extraction rule of abnormal data in log data and storing the abnormal data; constructing a data state transition table of the log data, and obtaining a state transition probability of the log data; according to the state transition probability of the log data, performing high-frequency sampling on the log data, performing calculation to obtain a transition probability of the abnormal data, and obtaining a feature matrix of the abnormal data; and establishing an abnormal judgment function, and according to the feature matrix, performing locating judgment on a root cause of system abnormality. The problem of how to perform network and system abnormality judgment and maintain information security in a big data environment is solved.