Two novel quinomycins I (1) and J (3) were discovered by UPLC-MS, then the two novel compounds and five known quinomycins A(2), B(4), E(5), C(6) and monosulfoxide quinomycin (7) were isolated from the culture broth of Streptomyces sp. HCCB11876. The structures of these compounds were elucidated through MS and NMR spectroscopic analysis. Compounds 1-7 showed significant antibacterial and cytotoxic activities. The structure-activity relationship indicated that sulfoxide group in N-methylcysteine of quinomycins (1, 3 and 7) would significantly decrease the antibacterial and cytotoxic activities. Moreover, the antibacterial and cytotoxic activities were decreased with the increase of carbon chain in amino-acid residues.