Long　non-coding　RNAs　(lncRNAs)　have　been　identified　as　new　regulatory　factors　in　tumor　progression.　Lymphoid　enhancer-binding　factor　1　antisense　RNA　1　(LEF1-AS1)　was　a　recently　identified　lncRNA.　This　research　aimed　to　investigate　the　roles　and　mechanisms　of　LEF1-AS1　in　colorectal　cancer　(CRC).　We　firstly　showed　that　LEF1-AS1　expression　was　upregulated　in　human　CRC　tissues　and　cell　lines.　LEF1-AS1　upregulation　was　demonstrated　to　be　induced　by　CREB1.　Clinical　study　revealed　that　high　LEF1-AS1　expression　was　positively　associated　with　histological　grade,　lymph　nodes　metastasis,　and　decreased　survivals　of　CRC　patients.　Functionally,　down-regulation　of　LEF1-AS1　using　si-LEF1-AS1　decreased　cell　growth,　migration　and　invasion,　as　well　as　increased　apoptosis　in　CRC　cells.　Mechanically,　LEF1-AS1　functioned　as　competing　endogenous　RNA　(ceRNA)　for　miR-489　to　positively　recover　DIAPH1,　thus　playing　an　oncogenic　role　in　CRC　pathogenesis.　Overall,　our　observations　identified　a　novel　CRC-related　lncRNA　LEF1-AS1　and　discovered　a　critical　role　for　this　lncRNA　as　a　ceRNA　in　CRC　pathogenesis,　suggesting　that　it　may　serve　as　a　novel　biomarker　for　prognosis　and　act　as　a　therapeutic　target　for　CRC　treatment.