A fault diagnosis system, wherein the fault diagnosis system comprises a control unit, a first management board, a first pull-up unit, a second pull-up unit, a first pull-up switch, a second pull-up switch, and a plurality of central processing units (CPU 1, CPU 2); the first pull-up unit is electrically connected to the first pull-up switch, the second pull-up unit is electrically connected to the second pull-up switch, the control unit is electrically connected to the first management board, and the control unit is electrically connected to the first pull-up switch and the second pull-up switch separately; the control unit is configured to receive physical partitioning information sent by the first management board, and control, based on the physical partitioning information, the first pull-up switch and the second pull-up switch to be turned on separately, so that a fault indication signal of each central processing unit (CPU 1, CPU 2) is electrically connected to the first pull-up switch and the second pull-up switch separately to form a fault diagnosis line, and the fault diagnosis line comprises a line from the first pull-up unit, the first pull-up switch, the central processing units (CPU 1, CPU 2), and the second pull-up switch to the second pull-up unit; the first pull-up unit and the second pull-up unit are configured to pull up the fault indication signal of the fault diagnosis line to obtain a pulled-up target signal; and the first management board is configured to detect whether a level of the target signal is lower than a diagnosis threshold, and when the level of the target signal is lower than the diagnosis threshold, determine that a faulty central processing unit exists in the central processing units (CPU 1, CPU 2) on the fault diagnosis line. the first pull-up unit is electrically connected to the first pull-up switch, the second pull-up unit is electrically connected to the second pull-up switch, the control unit is electrically connected to the first management board, and the control unit is electrically connected to the first pull-up switch and the second pull-up switch separately; the control unit is configured to receive physical partitioning information sent by the first management board, and control, based on the physical partitioning information, the first pull-up switch and the second pull-up switch to be turned on separately, so that a fault indication signal of each central processing unit (CPU 1, CPU 2) is electrically connected to the first pull-up switch and the second pull-up switch separately to form a fault diagnosis line, and the fault diagnosis line comprises a line from the first pull-up unit, the first pull-up switch, the central processing units (CPU 1, CPU 2), and the second pull-up switch to the second pull-up unit; the first pull-up unit and the second pull-up unit are configured to pull up the fault indication signal of the fault diagnosis line to obtain a pulled-up target signal; and the first management board is configured to detect whether a level of the target signal is lower than a diagnosis threshold, and when the level of the target signal is lower than the diagnosis threshold, determine that a faulty central processing unit exists in the central processing units (CPU 1, CPU 2) on the fault diagnosis line.