Abstract: In order to accelerate the process of making variational 2D mechanical drawing, graphic primitives such as lines and arcs are linked together according to certain correlation constraints to form structural elements with specific functional meanings. A single vector is used to determine the positioning, orientation and main control dimension of each structural element in a part drawing. Three kinds of correlation constraints are worked out to uniquely describe the way of assembling structural elements into the desired part. In such a way, the structural variational design of mechanical part is realized quite easily and quickly.