Changing the process of jet vortex spun yarn will result in the change of its structure, and further changing its properties. In this article a comparative study is carried out about three aspects, namely the internal structure of the nozzle, the internal flow field distribution of the nozzle, and the yarn properties of MVS861 and MVS870. The correlation between the yarn formation process and yarn properties will be discussed theoretically, which will be validated by designed experiments. There is significant meaning for researching the correlation between yarn formation process and yarn structure because, on the one hand, it can optimize the process of yarn formation and improve the structure of key components used to form yarn, and on the other hand, it can guide theoretically the design of the yarn structure.