Objective To construct an internet hospital critical children identification system based on Pediatric Assessment Triangle (PAT), and to evaluate its assessment accuracy. Methods According to the system development program, an internet hospital critical children identification system based on PAT was constructed. Forty standardized cases were collected, the condition of the children was judged using the system by 4 pediatric medical staff of internet hospital, and the reliability of the system was evaluated by simulation evaluation method. Then the condition of 644 children were assessed by 2 pediatric triage nurses using the PAT offline and 15 pediatric medical staff in internet hospitals using the system, and the diagnostic test evaluation system was used to evaluate the assessment accuracy of the system. Results The ICC of the 4 raters was 0.665, and the retest reliability was 0.527-0.899 (all P<0.05). The sensitivity of the system for appearance, respiration, circulation and identification of critical children in the PAT was 70.0%, 86.7%, 50.0%, 80.0%, and the specificity was 79.3%, 93.6%, 99.7%, 73.5%, respectively. The Youden index was 0.493, 0.803, 0.497, 0.535 (all P<0.05). Conclusion The consistency, stability and accuracy of the internet hospital critical children identification system based on PAT are satisfactory, which has certain clinical value.