To study the chemical constituents from a culture of the genetically engineered strain Streptomyces bingchenggensis BCJ60.All compounds were isolated and purified by various column chromatographies,including silica gel,Rp-18 and Sephadex LH-20,and their structures were elucidated through the interpretation of NMR and MS spectroscopic data.Eleven milbemycin derivatives were isolated from methanol extract of Streptomyces bingchenggensis BCJ60,which were identified as 3,4-dihydro-3-hydroxy-5-oxomilbemycin A3 (1),3,4-dihydro-3-hydroxy-5-oxomilbemycin A4 (2),seco-milbemycin C (3),seco-milbemycin A (4),milbemycin H (5),milbemycin β₁₃ (6),milbemycin ST906 (7),milbemycin β₃ (8),25-ethylmilbemycin β₃ (9),milbemycin β₆ (10) and milbemycin β₇ (11).Compounds 1 and 2 were new compounds.Compounds 1 and 2 possessed potent activities against Tetranychus cinnabarinus (LC₅₀ = 0.121 ± 0.010 mg/L and 0.116 ± 0.015 mg/L) and Bursaphelenchus xylophilus (LC₅₀ = 5.217 ± 0.064 mg/L and 5.581 ± 0.059 mg/L),which were comparable to those of commercial pesticide milbemycins A3/A4.