Abstract: Binding energy and energy level of an exciton in monolayer MoS2 are calculated by using the dielectric screened hydrogen model. By comparing with the results calculated via Bohr hydrogen model in two -dimensional space，it is found that the dielectric screening gives rise to a larger binding energy in exciton excited states and smaller level spacing between excited states and ground state. As a result，only when the principal quantum number is larger than 8，the quantization disappears and the exciton show a continuous energy level spectrum.

Key words: monolayer MoS₂, exciton energy level, dielectric screening;, Bohr hydrogen model