Preparation method and device of spinnable mesophase pitch

The invention relates to a preparation method and device of spinnable mesophase pitch. According to the preparation method, polymerization of different components in different temperature zones is realized based on self-migration of asphalt as a mixture with different molecular weights under thermal action, so that molecular weight distribution is narrowed. The device comprises a vertical tubular reactor, a cavity used for reaction in the vertical tubular reactor is of a hollow cylinder shape, and the length-diameter ratio of the hollow part is (10-40): 1. The preparation method comprises the following steps: carrying out segmented temperature control and inert atmosphere protection on the cavity, continuously feeding asphalt from the top of the cavity, continuously discharging the asphalt from the bottom of the cavity, and carrying out gradient non-isothermal polymerization to obtain the spinnable mesophase asphalt. The mesophase of the prepared spinnable mesophase pitch is in a wide-area streamline shape, t