Liquid crystal polyester, molding composition composed of liquid crystal polyester and application of molding composition

The invention discloses liquid crystal polyester, a molding composition composed of the liquid crystal polyester and an application of the molding composition. The liquid crystal polyester is composed of repetitive structural units represented by the formula I and the formula II; according to 100 mol% of the total amount of the repetitive units, the amount of the structural unit [I] derived from p-hydroxybenzoic acid is greater than or equal to 50 mol%, preferably greater than or equal to 66 mol% and less than or equal to 85 mol%; the amount of the structural unit [II] derived from 6-hydroxy-2-naphthoic acid is less than or equal to 50 mol%, preferably greater than or equal to 15 mol% and less than or equal to 34 mol%; through dynamic thermal mechanical analysis DMA testing, the liquid crystal polyester meets a condition that the energy storage modulus release rate [delta]G defined by the following formula (1) is greater than or equal to 95.0% and less than or equal to 99.7%, wherein the formula (1) is [delta]G=[G(-50)-G(melting point)]/G(-50)*100%. The liquid crystal polyester and the molding composition prepared by the liquid crystal polyester have the advantages of relatively high liquidity, excellent melting characteristics, and high forming stability of small thin-wall molding products, and are particularly suitable for use in thin-wall electronic preparation parts.