With the enhancement of people's awareness of environmental protection, environmentally friendly polyvinyl chloride (PVC) plastic additives are constantly promoted, and the use of natural mineral vermidemite to replace non-environmentally friendly PVC plastic additives has become a new trend in the industry. A vermiculite sheet suspension was obtained by a liquid high-speed shear/grading centrifugal method, and the vermiculite nanosheet/polyvinyl chloride (PVC) composite plastic was prepared via solvent substitution. The influence of the content of vermiculite nanosheet on the ultraviolet, thermal conductivity, thermal stability and flame-retardant performance, tensile properties was investigated. The results show that the sizes of vermiculite are 150 nm-1.1 μm, and the original structure of vermiculite preserves. When the content of vermiculite nanosheet is 15% (in mass), the tensile strength of vermiculite nanosheet/PVC composite plastic is increased by 50.8%, the limit oxygen index value is increased by 7.3%, the thermal conductivity is decreased by 17.8%, and the aging heat stability time is increased by 140 min, and the dehydrothermal degradation time is increased by 24 min. This composite plastic has superior thermal stability and ultraviolet resistance. Adding vermiculite nanosheet into PVC can improve the properties of composite plastic, which has a practical significance in the preparation of high-performance PVC product.