In order to solve the transverse vibration problem of two-span continuously modified Timoshenko beam on viscoelastic four-parameter foundation，a new vibration governing equation is established by combining two-span continuously modified Timoshenko beam with viscoelastic four-parameter foundation. By using the echo matrix method，bisection and golden section method，the relation and difference between the natural vibration characteristics of two-span（equal-span，unequal-span）continuously modified Timoshenko beam and single-span modified Timoshenko beam on viscoelastic four-parameter foundation are analyzed. The results show that for the modified Timoshenko beam on the viscoelastic four-parameter foundation，the natural frequency of each order of the single-span beam is less than that of the two-span continuous beam，the even-order natural frequency and attenuation coefficient of the single-span beam are the same as the odd-order natural frequency and attenuation coefficient of the two equal-span continuous beam，and the odd-order natural frequency of the unequal-span two-span continuous beam is less than that of the two-span continuous beam. The even-order mode shapes of two equal-span continuous modified Timoshenko beams are symmetrical with respect to the supports in the middle of the span，and the odd-order modes are antisymmetric with respect to the mid-span.