The stability of axially accelerating viscoelastic beam was investigated when the principal parametric resonanceor combination porametric resonance was excited. The material time derivative was used in the viscoelastic constitutive relation. When the axial speed variation frequency approaches the sum of two arbitrary natural frequencies or the twice of arbitrary natural frequency, the summation or principal parametric resonance may occur. The method of multiple scales was employed to directly solve the governing equation of axially accelerating viscoelastic beam. Analytical expressions of the instability boundary were obtained for summation and principal parametric resonance. Finally, numerical examples show the effects of viscosity and axial disturbing tension for instability region.