In order to accurately assess the real-time operating conditions of a grid-connected wind turbine dviven generator system（WTGS） while referring to the on-line monitoring information， a matter-element assessing method for the operating conditions is proposed. Firstly， by analyzing the monitored physical quantities of the control system of a WTGS， an evaluation indicator system of operational conditions for a grid-connected WTGS is constructed that can reflect the important operational characteristics of the WTGS. Secondly， by using a method of Bin， the evaluation indicators of the monitoring temperature values are analyzed respectively， and the concept of inferiority indicator is introduced to quantify all evaluation indicators. Thirdly， by using both the analytic hierarchy process（AHP） method and equalization function， the comprehensive weights are calculated. In addition， by referring to the extended relation functions in the matter-element analysis theory， the matter-element assessing model of the operating conditions for the WTGS is developed. Finally， based on the actual monitoring data of a 850 kW WTGS within a period of time， the operating conditions are evaluated with the matter-element method proposed. A comparison with the actual operation conditions shows that the assessment method and model proposed are effective.