In order to recognize the morphogenesis and its application in the taxonomic identification of fish larvae and juveniles in genus Myctophum Rafinesque,1810,larvae and juveniles samples collected during the oceanographical expedition cruises,which were carried out in central and western tropical Pacific during April 1978 to June 1979 and in Kuroshio Current extension regions of the East China Sea during April 1984 to June 1986,were identified separately based on the references related to the morphological and taxonomic features of this genus.The authors identified the larvae and juveniles of Myctophum spinosum(Steindachner,1867),M.nitidulum Garman,1899,M.asperum Richardson,1845,M.punctatum Rafinesque,1818,M.aurolaternatum Garman,1899,M.orientale(Gilbert,1913),M.obtusirostris Tning,1928 and Myctophum sp.,and described their ontogeny in morphological characteristics in detail.Combined with the morphological characteristics of M.phengodes,M.lychnobium,M.selenops,M.brachygnathum,Myctophum sp1.and Myctophum sp2.from the references,the identification key to these fourteen species of Myctophum distributed in the world,including eleven species with morphological characteristics already known and other Myctophum speices which allows identification at the genus level,has been established.The result showed that all but M.aurolaternatum larvae and juveniles in genus Myctophum were observed with enlarged fan-shaped pectoral fins.The head somewhat flat was in a triangular shape with non-spherical eyes on elongate stalks or with well developed conical choroid mass.Pigments were distributed on the jaws,isthmus,opercle,branchiostegal membrance and pectoral fin base.Pigment patterns on lateral gut were evenly distributed on trailing section,except heavier near terminus.The jaws were full of sharp teeth.A single adipose fin was found on the back behind the dorsal fin.All these were the common characteristics of larvae and juveniles in genus Myctophum.M.aurolaternatum larvae had unique morphological characteristics:very flat head,eyes small on distinct elongate stalks,and with straight gut trailing at midbody and extending well beyond caudal fin.The shape of the choroid tissue or whether they own elongate stalks to the eyes;whether there were melanophores at the anterior tip of the lower or upper jaws;pigment pattern on the pectoral fin base,between the pectoral fin rays and in lateral gut;whether there was melanophores distributed on the tip of tail,the trailing edge of the anal fin and adipose fin were the distinct categories identification and morphological characteristics in larvae and juveniles in genus Myctophum.