Abstract: We explored the system output response of the linear harmonic oscillator in the natural frequency influenced by the white noise and the simple harmonic excitation conditions,and found that the output response was a simple harmonic vibration,and the vibration frequency was an excitation force frequency.The amplitude showed that stochastic resonances occured with the variations of the frequency of the simple harmonic excitation force and the natural frequency via the calculation of the analytic expressions of the first-order moment.