该方法依赖WMI的系统服务，该服务一般不会被关闭；但如果系统服务缺失或者出现问题，该方法无法取得MAC地址，需要重启Windows Management Instrumentation服务。

public static string GetMacAddress() { try { string active_mac = ""; ManagementClass mc = new ManagementClass("Win32_NetworkAdapterConfiguration"); ManagementObjectCollection moc = mc.GetInstances(); foreach (ManagementObject mo in moc) { if ((bool)mo["IPEnabled"] == true) active_mac = mo["MacAddress"].ToString(); mo.Dispose(); } string mac = active_mac.Substring(0, 2) + active_mac.Substring(3, 2) + active_mac.Substring(6, 2) + active_mac.Substring(9, 2) + active_mac.Substring(12, 2) + active_mac.Substring(15, 2); return mac; } catch (Exception ex) { return "Error Mac." + ex.Message; } }