In physics，heat energy divided by temperature ，entropyis obtained, which means the conversion degree from heat to work. While in science and technology field, entropy generally refers to possible degree of certain matter system status. In social science area, entropy indicates the degree of certain society state, in the field of information theory, entropy expresses uncertain degree. In a word, the application of �entropy� is widely used. However, there�s no scientific theory support for deciding weighing by entropy evaluation method. This paper give a detailed explanation of it in three aspects to demonstrate that scientific is not decide weighing by entropy evaluation method.