The nesting problem of irregular shapes has not been solved completely so far. This paper introduces case (master drawing) based reasoning method for solving nesting problem and presents the structure frame of nesting system based on the master drawings. The key aspect of this method is shape matching, which can be described as when the spare groups and board are provided, how to retrieve corresponding master drawing from drawing database. A similarity retrieval algorithm for master drawings is proposed in this paper based on the Findler distance between pattern strings of the shapes' simplified skeletons. A numerical example shows the method is effective.