Rhodobacter sphaeroides is a kind of high yield coenzyme Q10 of photosynthetic bacteria.The medium composition and fermentation conditions for production of coenzyme Q10 by R.sphaeroides EIM-8 were optimized.Optimization of medium was performed by single factor and response surface design.The optimized medium composition was as follows: glucose 27.8 g/L,(NH4)2SO4 4.9 g/L,glutamic acid 4.7 g/L,corn steep liquor 2.5 g/L,MgSO4 9.5 g/L,FeSO4 1.5 g/L,NaCl 3.5 g/L,KH2PO4 4.0 g/L,auxiliary liquid 15.0 mL/L.The culture condition determined by single factor experiment was as follows: initial pH 6.5,temperature 32 ℃,inoculum 10%,medium volume 40 mL/250 mL.Using the described medium and condition,coenzyme Q10 yield could reach 128.9 mg/L which was 89.0% higher than results prior to optimization.