Drawing the intersection of two curved faces is an important issue in technical drawing. There are two types of problem: a special case when one of the two curved surfaces is a cylinder and a general case with any two curved surfaces. In principle, it is necessary to find the projections of some necessary points, then connect the intersection line according to the defined form. The connection of the line in any order is a difficult problem. The article presents the rule of how to connect the line of the problem of a cylinder intersecting with a number of curved surfaces. In addition, the article also shows how to apply the theoretical problem of assigning two curved surfaces and the observed - hidden rule in the practice of drawing a single-cross shape.