Traditional work of quantity survey is time consuming and low quantity. To do the work automatically by computer is a good solution. A rule-based system for interpretation of vectorized construction drawings automatically (AISD) is presented in this paper. Based on summarizing the features and rules, it recognizes graphical primitives and symbols in construction drawings, analyzes relationships between them, interprets information of construction element and calculates the quantity of reinforcement steel. Based on the study of features of construction drawings,a group of rules are developed for interpretation of different kinds of construction drawings.Experimental results show that it provides a sound solution for understanding and interpretation of construction drawings.