Objective To evaluate whether patients aged over 70 years old is an independent predictor for prolonging the waiting time, and to know whether the population can be prioritized in the emergency grading system.Methods A retrospective analysis was conducted. All the clinical data of adult visitors to the emergency department of the Third Affiliated Hospital of Sun Yat-sen University from January 1st in 2016 to December 31st in 2017 were collected. All the patients received four emergency first aid triages and treated according to the emergency classification results. The relevant data of selected patients were retrieved from the hospital information system (HIS) including gender, age, triage level, triage department, outpatient service and initial diagnosis time. According to the conclusion of pre-phase analysis that the patients over 65 years old was not associated with waiting time, all subjects were divided into ≥ 70 years old group and < 70 years old group for further analysis. The waiting time was defined as the difference in registration time and the initial diagnosis time, and the patients were divided into two groups according to whether it exceeded the target waiting time (TWT). TWT was considered as follows according to each emergency triage level: level Ⅰ instantly, level Ⅱ10 minutes, level Ⅲ 30 minutes, level Ⅳ 60 minutes (subacute patients) or 2-4 hours (non-urgent patients). The multivariable Logistic regression analysis was conducted to determine whether the factor that aged over 70 years old was an independent predictor for prolonging waiting time over TWT.Results There were 272989 adult visits recorded totally, of which obstetrics and gynecology department visits, incomplete personnel information, invalid diagnosis (or no diagnosis), triage levelⅠ, abnormal waiting time (the waiting time exceeded 99％ of the average waiting time of all samples) records were excluded. Finally, 219299 emergency patients were enrolled, with 102218 male and 117081 female, which showed an average age of (35.86±15.81) years, 208082 patients (94.9％) in < 70 years old group, and 11217 (5.1％) in ≥ 70 years old group. Totally 191588 patients (87.4％) were diagnosed within the TWT, and the number was 86.5％ (9701/11217) in the ≥ 70 years old group. Multivariate Logistic regression analysis indicated that age under 70 years old was independently associated with an exceeded TWT [adjusted odds ratio (OR) = 1.106, 95％ confidence interval (95％CI) = 1.041-1.176,P = 0.001]. Meanwhile, visits during the peak period or low triage level was also a risk factor of exceeded TWT. According to the Logistic regression analysis of different departments and removing other factors, in the emergency internal medicine with the most elderly patients, the probability of exceeded TWT in ≥ 70 years old group was lessened (adjustedOR = 1.203, 95％CI = 1.121-1.291,P < 0.001).Conclusion In the emergency pre-grading system, the elderly aged (≥ 70 years old) was more likely to see a doctor in TWT than those under 70 years old, so they were easy to get priority treatment.