Abstract: This paper provides a short commentary on the methodological cont roversy surrounding valuation of world ecosystem services. A new conceptual framework is then proposed for understanding the value of biodiversity , and , based on this , a number of issues are discussed , involving measuring the value of biodiversity , which have not yet been resolved. These are the computability of value , the validity of valuation methods , the additivity and analyticity of value sectors , and error measurement of the value. Finally the paper presents methodological frameworks for two important issues of conservation economics , one of which is estimation of the cost of biodiversity disturbance , and the other is costbenefit analysis (CBA) and cost-effectiveness analysis (CEA) for conservation engineering.