Objective To investigate the effect of an automated physiological track-and-trigger warning system designed based on the Modified Early Warning Score (MEWS) incorporating oxygen saturation and urine volume to identify elderly patients after general surgery at risk of deterioration. Methods A total of 120 elderly patients after general surgery were randomized into a control group and an intervention group of 60, receiving either routine monitoring after the surgery or monitoring using the automated physiological track-and-trigger warning system designed based on the adjusted MEWS. Results Compared with the control group, the intervention group had shorter length of hospital stay after the surgery (P<0.05). There were no significant differences in the counts of vital signs monitoring, the rates of transfer to ICU and adverse nursing events between the two groups (P>0.05 for all). Conclusion Implementation of an automated physiological track-and-trigger warning system based on the adjusted MEWS can help nurses judge patient′s condition in a short time, shorten length of hospital stay, and would not increase nurses′ workload of vital signs monitoring.