The increase in the grid-connected capacity of the wind turbine indicates that the renewable energy alternative is gradually developing. However, the nonlinear system containing wind power may stimulate multi-mode forced oscillation, whose deep relationship is difficult to analyze by traditional methods. In this paper, the characteristics of wind-induced forced oscillations are analyzed firstly based on combined wind speed model. Secondly, bispectral analysis and bicoherence analysis are introduced. The obtained bispectrum and bicoherence coefficients are used to analyze the oscillation caused by wind power and the quadratic phase coupling level between these oscillation modes. Finally, the simulation is operated in the four-generator two-zone system with a small wind farm. The simulation results verify the correctness of the proposed speculation and the effectiveness of the proposed method.