A bstract We study the semileptonic and non-leptonic charmed baryon decays with SU(3) flavor symmetry, where the charmed baryons can be B c  = (Ξ c 0 , Ξ c + , Λ c + ),  B c ′  = ( Σ c (++,+,0) , Ξ c ′ (+,0) , Ω c 0 ),  B cc  = (Ξ cc + + , Ξ cc + , Ω c + ) or  B cc  = Ω ccc + + . With B n (′) denoted as the baryon octet (decuplet), we find that the B c  →  B n ′ ℓ + ν ℓ decays are forbidden, while the Ω c 0  → Ω − ℓ + ν ℓ , Ω cc +  → Ω c 0 ℓ + ν ℓ , and Ω ccc + +  → Ω cc + ℓ + ν ℓ decays are the only existing Cabibbo- allowed modes for B c ′  →  B n ′ ℓ + ν ℓ ,  B cc  →  B c ′ ℓ + ν ℓ , and  B ccc  →  B cc (′) ℓ + ν ℓ , respectively. We predict the rarely studied B c  →  B n (′) M decays, such as ℬ Ξ c 0 → Λ 0 K ¯ 0 , Ξ c + → Ξ 0 π + = 8.3 ± 0.9 , 8.0 ± 4.1 × 10 − 3 and ℬ Λ c + → Δ + + π − , Ξ c 0 → Ω − K + = 5.5 ± 1.3 , 4.8 ± 0.5 × 10 − 3 . For the observation, the doubly and triply charmed baryon decays of Ω cc + → Ξ c + K ¯ 0 , Ξ cc + + → Ξ c + π + , Σ c + + K ¯ 0 , and Ω c c c + + → Ξ cc + + K ¯ 0 , Ω cc + π + , Ξ c + D + are the favored Cabibbo-allowed decays, which are accessible to the BESIII and LHCb experiments.