Four known compounds had been isolated from the Streptomyces sp. YIM66017, and their structures were elucidated by spectral analysis as 2,6-dimethoxy terephthalic acid (1), yangjinhualine A (2), alpha-hydroxyacetovanillone (3) and cyclo(Gly-Trp) (4). Compound 1 was isolated from natural resources for the first time, and compounds 2-4 were isolated from streptomycetes for the first time. The 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity assays showed that 1 showed higher activity than rutin with IC50 of 4.61 mug/mL and 2 showed the activity with IC50 of 57.12 mug/mL.