The invention relates to a two-dimensional transition metal carbide (nitride) and nano sulfur particulate composite as well as preparation and application thereof. The composite is formed by two-dimensional transition metal carbide (nitride) MXene nanosheets and nano sulfur particles, wherein the nano sulfur particles grow on the surface of the two-dimensional transition metal carbide (nitride) MXene nanosheets in an in-situ manner, marked as S@MXene. The stable suspension of a single layer or a few layers of two-dimensional transition metal carbide (nitride) MXene nanosheets is mixed with a sodium thiosulfate or sodium polysulfide solution; with formic acid as a reducing agent, the nano sulfur generated by the reaction uniformly grows on the surface of the two-dimensional MXene nanosheet; and the two-dimensional transition metal carbide (nitride) and nano sulfur particulate composite is obtained through neutralization, washing and centrifugation and serves as the anode of a lithium-sulfur battery. According to the invention, a high-conductivity two-dimensional transition metal carbide (nitride) MXene nanosheet carrier is uniformly compounded with nano sulfur particles, introduction of a binder and a conductive agent is not needed, and the composite has excellent electrochemical performance as the anode of a lithium-sulfur battery; and moreover, the technology is simple and can meet the requirements of large-scale production.