With the gradual aggravation of environmental pollution and energy shortage, both developing technology on non-pollution environmental restoration and exploring project on alternative clean energy have recently become a very important and quite urgent task. As one of the transition metal sulfides with layered structures similar to graphene, molybdenum disulfide(MoS₂) has become a research hotspot in the field of photocatalytic environmental remediation and clean energy(hydrogen generation) due to its narrow band gap, high reaction activity of the edges, and ease of forming a composite structure with other substances. This paper mainly introduces the synthesis methods, photocatalytic degradation and hydrogen generation behaviors of the MoS₂ and its composites. Detailed methodologies for the synthesis of semiconductor MoS₂ and its composites, photocatalytic degradation activity of pollutants, photocatalytic hydrogen generation activity and the corresponding mechanisms are emphasized and illustrated by a great many of the typical examples. MoS₂ and its composites have displayed many advantages including environment friendliness, low cost and high efficiency in photocatalytic degradation of pollutants and photocatalytic hydrogen production. As the bright future materials, MoS₂ and its composites have a broad application prospect in the field of environmental restoration and clean energy with the further development of its general mechanism.