Although Acute Physiology And Chronic Health Evaluation (APACHE) and Simplified Acute Physiology Score (SAPS) show good predictive effect on critically ill patients, they may have predictive data migration or poor population calibration when being used in the elderly critically ill patients. However, the established special prediction models for elderly are not of enough accuracy and reliability. So, frailty syndrome has become the key point in geriatric comprehensive assessment. Current studies showed that frailty index (FI) and clinical frailty scale (CFS) can be used as the objective models to assess frailty syndrome, and have become hotspot in the studies on predictive assessment for critically ill elderly. This article reviewed the development process and research progress of these predictive models, with a view of clinicians for better application.