With a simple model of shallow-water on an equatorial beta plane, the nonlinear equatorial Rossby waves in a shear flow with beta effect are investigated by the asymptotic method of multiple scales. The nonlinear Schrdinger equation, satisfied by large amplitude Rossby envelope solitary waves in shear basic flow with beta effect, is derived. The effects of basic flow shear and beta effect on the nonlinear equatorial Rossby waves are also analyzed.