It is difficult to evaluate the anaethetic availability of operation under acupuncture anaethesia, because none of the essay method (except lingiustic method) is ready accessible to usual practise. This paper put forward a method which is based on the concept of Zadeh for the purpose of evaluation. The possibility evaluation are taken as the following: 1. Select a numerical value which expresses the anaethetic availability, we call it Pain-Index and is defined as P = ∑ i 10 r i t i where the subscript i is a mark to express the step in various operation, and t, r are records of the corresponding time and pain response respectively. The pain response is devided into 4 grades, which are marked with ”0”, “+”, “++”, “+++” to express “no pain”, “slight pain”, “mid pain” and “strict pain” respectively. And as we know, that the grades are closely related to the pain response, so that we need a value of P, be used as a standard, to evaluate the availability of acupuncture anaethesia. 2. Classify the cases of operation under acupuncture anaesthesia into 4 groups as traditional method, and plot a histogram of PI with respect to the number of cases. 3. We take as S-type function, by the histogram, and draw up a suitable possibility distribution. 4. We assign a qualification to the possibilty distribution and the linguistic representation is expressed by the valus of α -possibility. For example, we take 26 cases of appendectomy under acupuncture anaethesia as a random sample, and cases is evaluated by the traditional method and ours, the results are the same, but the later is better applied to some special cases.