Jeremy Bentham put forward a calculation of pleasure and pain in his utilitarian theory，asking for a quantitative estimation of pleasure and pain，so that pleasure or pain caused by any actions or events can be more accurately estimated.Based on the result，people and government can choose the plan that brings great pleasure to most people.However，this method of calculation of pleasure and pain was criticized by some later philosophers.John Stuart Mill，who claimed to be Bentham's successor，made modifications to this calculation theory to defend Bentham.He expanded the pleasure of only difference in quantity into the difference in quantity and quality，and refined the rough concept of“pleasure”. “Happiness”proposed by Mill is more abundant than“pleasure.”However，these minor details of Mill's theoretical modification did not free Bentham's calculations from numerous criticisms.In the actual estimation process，Bentham's calculations still face practical problems.