Abstract: There are plenty of methods used for the assessment of organic compounds biodegradability, but lack of comprehensive literatures in systematically introducing the assessment methods and guiding the choice of the methods. This paper briefly introduced the indicative parameters in assessing organic compounds biodegradability and the assessment methods of aerobic and anaerobic biodegradation, with the focus on the principles and criteria in the choice of the assessment methods, and analyzed in detail the reasons for the differences in the biodegradation rates of organic compounds when different test methods were adopted. Taking the standards established by the Organization for Economic Co-operation and Development (OECD) as an example, the process of choosing and applying the assessment methods was introduced, the systematic method-choosing route was integrated, and the advantages of the OECD standard methods were pointed out.