The objective of the present study was to determine the effects and mechanisms of dietary sea buckthorn pomace (SBP) supplementation on intramuscular fat (IMF) accumulation in LD muscle of ram lambs. A total of 30 Dorper × thin-tailed crossed ram lambs (4 months old) were randomly selected and equally assigned into 3 groups: control, 7.8SBP and 16SBP, which received 3 levels of SBP supplementation (0%, 7.8% and 16%). After experiment, the crude fat was determined by Soxhlet extraction, the number of mature adipocytes were determined by Masson trichrome staining. The real time-qPCR were used to determine key gene’s expression and Western blotting were used to analyze protein alteration. Additionally, ELISA was employed to analyze enzyme’s activity. Compare with control lambs, the WBSF in both 7.8SBP and 16SBP groups were decreased (P<0.01). The crude fat content in LD muscle of 16SBP was increased (P<0.05), together with higher mature adipocytes number (P<0.05). The mRNA content of key adipogenic related genes, including ZNF423 (P<0.05), PPARγ (P<0.05) and C/EBPα (P<0.01) were upregulated by the supplementation of 16%SBP. Consistently, both the C/EBPα and PPARγ content in LD muscle of lambs were higher compared with those from control group. SREBP1 was unregulated (P<0.05) in LD muscle of 16SBP lambs both at mRNA and protein level. Meanwhile, both mRNA (P<0.05) and enzymatic activity (P<0.05) of FAS were higher than that in control group. Moreover, ACC’s activity was significantly upregulated (P<0.05). Additionally, although both MDH and LPL activity were not affected by SBP supplementation, a reduced HSL activity was observed in lambs received 16% dietary SBP. Dietary 16%SBP supplementation effectively promoted intramuscular adipogenesis related transcriptional factors expression, and regulated triglyceride metabolisms through enzyme’s activity manipulation, which might be contributed to reduce WBSF.