There exists much controversy concerning the genesis of myrmekite, and most geologists hold that myrmekite is of metasomatic origin. Myrmekite occurs invariably in granulite facies metamorphic rocksand corresponding migmatitesand isoften found among plagioclase , orthoclase and quartz; the index of refraction of myrmekite-bearing plagioclase is lower than that of plagioclase without myrmekite. Based on these facts and taking into account the achievements obtained in recent experimental research on melting of granite rocks, the author considers that myrmekite is eventually formed by eutectic crystallization in the process of cooling and crystallization after granitic melts are formed through anatexis under the condition of granulite facies metamorphism.