Objective　To establish simple and accurate evaluation standards for access preparation of molar and verify its reliability. Methods　9 undergraduate students who had entered the intership for one month prepared access of molars in vitro. 10 dentists specialized in endodontics for over 5 to 15 years evaluated the molars according to the evaluation standards. Intraclass correlation coefficient of the results was analyzed by SPSS statistics. Results　The intraclass correlation co-efficient of the evaluation given by 10 endodontists was 0.739 (P=0.000)

which had statistical significance. The result was between 0.61 and 0.80

meaning the evaluation standards were moderately reliable and applicable among different observers. Conclusions　The evaluation standards proposed in this study are reliable and has not been influenced by the clinical experience of observers. And it is worth further exploration and promotion.