Objective: To indentify Optimal cutoffs of grip strength for definition as weakness in the elderly. Methods: Our study population comprised 1317 subjects (mean ± SD age: 67.6 ± 6.0 years; 44.3% men) from the Hangu area of Tianjin, China. Data collection includes general physical examination, biochemical indicators and questionnaire. Mobility limitation was defined as a 4-m walking speed < 0.8 m/s and grip strength represents muscle strength. According to the ROC curve model, the cut-off point of grip strength was calculated, when mobility limitation was selected as the target variables. Results: According to the results of ROC curve, In man, grip strength is lower than 32.45 kg, the strength is weaker, Sensitivity is 79.7% and Specificity is 64.9%, the AUC is 0.764 (p < 0.001); In women, grip strength is lower than 18.20 kg, the strength is weaker, Sensitivity is 53.3% and Specificity is78.1%, the AUC is 0.703 (p < 0.001). Conclusions: Cut points for weakness derived from this large, diverse sample of older adults may be useful to identify populations who may benefit from interventions to improve muscle strength and function.