In this paper, a two-dimensional numerical model for wave-seabed-pipeline interaction is developed to examine the wave-induced uplift force onto pipelines buried in sloping seabeds. The Reynolds-averaged Navier stokes equation and the poro-elastic equation are used to simulate the wave motion and seabed response, respectively. Meanwhile, the pipeline is considered to be elastic. Firstly, three laboratory experiments are taken to verify the effectiveness of the numerical model. Then, the effects of pipeline characteristics, soil properties and wave parameters on the nonlinear wave-induced uplift force onto a pipeline buried in a sloping seabed are analyzed. Finally, an empirical formula for predicting the nonlinear wave-induced uplift force onto buried pipelines under different slope angles is proposed. It can be found that the slope angle can greatly affect the nonlinear wave-caused pore pressure response, as well as the uplift force onto the pipeline. Moreover, the simple method for predicting the uplift force proposed in this paper can facilitate engineering applications.