To study on the form of coenzyme Q₁₀ (CoQ₁₀) in soft capsule toselect the suitable method. MethodsBased on the chemical property of CoQ₁₀, the existing formsweredetermine in soft capsulethrough chromatography performance of different methods. And then the methods were selected for different forms of CoQ₁₀. ResultsCoQ₁₀ (oxidized form) and reduced CoQ₁₀ co-exist. The methods in China including China National Standard (GB), Chinese Pharmacopoeia (ChP) areboth aimed to the oxidized form.Inthe methods of Association of Official Analytical Chemists (AOAC)and United State Pharmacopoeia (USP), the reduced CoQ₁₀ is transformed to CoQ₁₀ first, and then the total amount is determined.ConclusionCoQ₁₀ (oxidized form) and reduced CoQ₁₀ co-exist in soft capsule and transform to each other under suitable conditions. When testing CoQ₁₀ in soft capsule, the method should considerif there is only the oxidized form or the two formsboth.