Since the outline of the flexible printed circuit (FPC) is complex and changeable and the pins are densely distributed in some regions of the layout, it is difficult to route all nets completely. In this paper, we propose a partition algorithm for complex FPC to divide the FPC routing problem into escape routing and area routing in order to better allocate the routing resource. Our algorithm is based on constrained Delaunay triangulation (CDT), several techniques are proposed to adapt it to FPC. These techniques are as follows: (1) a pin cluster dendrogram based on FPC outline information, which makes pin clustering result more accurate; (2) a ternary tree based on CDT to determine the escape boundary of each region; (3) an escape-passage-connection model (EPC model) to describe the topological connection relationship; and (4) a global dynamic routing graph based on CDT to calculate the crossing points on the escape boundaries and generate the topological path of each net without congestion. Experimental results on some industrial cases show that our method has great generalization ability, and the routing results are better than those without considering the area partition.