Abstract: A machine monitoring system includes a plurality of first machines and a control module. The first machines are for a first process. The control module is connected with the first machines. The control module is configured to: define each of the first machines as a high-risk first machine or a low-risk first machine according to a first risk score of each of the first machines; designate one of the first machines being defined as the high-risk first machine as a selected high-risk first machine; assign an object to be processed by the first process through the selected high-risk first machine to obtain a processed object; and determine whether to continue or stop to use the selected high-risk first machine according to a test result of the processed object.