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Introduction：In the long period of natural selection and artificial selection,people began to plant alfalfa for cattle feed on theGuanzhong Plain,the main production area of Qinchuan beef cattle.This resulted in tremendous improvements inQinchuan beef cattle,particularly in relation to its body size,work ability,and individual meat yield.Analysis of thebeef cattle transcriptome and its expression profile data are essential to extending the genetic information resourcesfor this species and would support studies on this animal.Materials and Methods：Using RNA-Seq,this study compared the transcriptomic landscapes of longissimus muscle from embryo at day 135 post fertilization versus 30-month-old adult cattle.Results：A total of 25605140 and 26214800 reads were sequenced for embryonic and adult pooled samples,respectively.We identified 24464-29994 novel transcript units in two pooled samples.In addition,8533一10144 genes showedevidence of alternative splicing,in agreement with the finding that alternative 3splicing is the most common typeof alternative splicing event in cattle.We detected the expression levels of 16174 genes, and 6800 genes exhibiteddifferential expression between the two pooled samples with a false discovery rate≤0.001.Using GO enrichmentand ICEGG pathway analysis,multiple GO term and biological pathways were found to be significantly enrichedfor differentially expressed genes.In addition,we discovered that 30618-31334 putative single nucleotidepolymorphisms were located in coding regions.Discussion：A majority of the annotated transcripts in the Ensembl database were covered by sequenced reads,illustrating thesensitivity of RNA-seq for transcript discovery,even for genes expressed at low levels.We also found thatalternative 3-end splicing is the most common type of alternative splicing event in cattle and that intron retention isthe least common alternative splicing mechanism.Our results are consistent with those of a similar pig study.However,these results contrast with those reported for humans and Holstein cows,where exon-skipping is the mostprevalent mechanism;the results also differ from those found for rice,forwhich intron retention is the primaryalternative splicing mode.