Neutral Beam Injection (NBI) is an important auxiliary heating and driving method for Tokamak devices. The ionization of neutral atoms determines the neutral beam heating(energy and particle deposition profile) andcurrent drive efficiency. In general, the attenuation characteristics of the neutral beam are simulated by using the background plasma parameters and neutral beam parameters, and then the heating and current driving effects of the Tokamak neutral beam are analyzed. Beam emission spectroscopy is a series of characteristic spectral lines radiated by the excitation and deexcitation process of electron and ion collision of neutral beam-injected plasma. The strength of Beam emission spectroscopy is affected by plasma density, temperature, energy beam, beam density and other factors, so neutral beam attenuation can be acquired using the beam emission spectrum. This paper analyses neutral beam attenuation under different plasma densities and different neutral beam energies on EAST. Comparing the experimental and Simulation of Spectra(SOS) results,the experimental and simulation results are in good agreement. The feasibility of obtaining neutral beam attenuation characteristics by measuring the Beam emission spectroscopy is verified.