The abstract results of Grillakis-Shatah-Strauss were used directly and the orbital stability and instability of solitary waves solutions for the generalized Boussinesq equations with two nonlinear terms were investigated.The general conclusions on the orbital stability of solitary waves were obtained.Furthermore,the explicit expression of discrimination d"(c) was deduced according to two exact solitary waves solutions of the equations.And the wave speed interval which makes the two solitary waves stable was given.Moreover,the influence of the interaction between the two nonlinear terms of the equations on the wave speed interval which makes the two solitary waves stable was also analyzed.Finally,the biggest wave speed interval which makes the two solitary waves stable was presented.