Steedman claims if the value is calculated according to the method of Karl Marx,then negative value will appear which leads to the coexistence of negative surplus value and positive profit.This conclusion,however,is wrong.The reason is that the basis on which he calculates the labor value of different productive process is not the social necessary labor time but nature time.In fact,there is no negative value even under the condition of joint production if the values in different productive process are determined by the social necessary labor time.So,the coexistence of negative surplus value and positive profit is impossible.