Transmission towers are essential components of power grids, and their stability is crucial for grid safety. These structures are often subjected to combined wind and ice loads, which can severely impact their performance. This study develops a three-dimensional finite element model of a typical tangent transmission tower-line system. Ice accretion is simulated using an equivalent density approach, and fluctuating wind loads are generated via wind spectrum analysis. Dynamic responses under coupled loading are analyzed, and operational risk states are classified. Results show that wind speed and ice thickness nonlinearly amplify structural responses. Using buckling strengths of Q235 and Q345 steels as failure thresholds, operational states are divided into safe, warning, and danger zones. The findings offer a theoretical basis for risk assessment and disaster prevention under complex meteorological conditions.