The invention relates to a method for preparing p-
xylene by separating and crystallizing mixed xylenes, and mainly solves the problem of large
energy consumption in a
crystal separating process in the prior art. To well solve the problem, the invention adopts the following technical scheme of preparing the p-
xylene by separating and crystallizing the mixed xylenes that: p-
xylene crystal I and
crystallization filtered stock I are obtained by crystallizing mixed xylenes in a primary crystallizer and separating
crystal mush; the crystal I is melted by heat exchange, is partially returned to a first
solid-liquid separator, and partially enters a product tank; the
crystallization filtered stock I is separated into two streams, one
stream returns to the crystallizer, and the other
stream entersa pulping tank; one part of crystal mush in the primary crystallizer is cleared so as to obtain clear
crystallization stock I which enters the pulping tank; p-xylene crystal II and crystallization filtered stock II are obtained by separating the crystal mush in a secondary crystallizer by a second
solid-liquid separator; the crystal II enters the pulping tank, and separated after mixed heat exchange so as to obtain p-xylene crystal III and crystallization filtered stock III; the crystal III is melted by heat exchange, is partially returned to a third
solid-liquid separator to be used as cleaning solution, and partially enters the product tank; the crystallization filtered stock II is separated into two streams, one
stream returns to the secondary crystallizer, and the other stream enters the pulping tank; the crystallization filtered stock II and the mixed xylenes are subject to heat exchange and enter a stock tank; and the clear crystallization stock II and the mixed xylenes are subjected to heat exchange and enter the stock tank. The method can be used in p-xylene industrial production.