Abstract: This paper gives a comprehensive analysis of the combination features of trace of the central volcanic structures.The basis of the results of elastic theoretical calculation,the evolutional features of photo elastic stress fields at the dynamic and the static state and the model experiments,the dynamic mechanism of their formation are proposed as follows.1.In a plane view,the combination features of structural trace of the central volcanic dome are that the concentric multi-loop fractures and radiation fractures are in a mozaic state with a common center,and the crater is situated at this center.The radiation fractures followed by the loop ones which are controlled by the former.In any case they can not be considered as a synchronous conjugated fracture system.The concentric multi-loop fractures appear in the plane as the intersection lines of the radiation fractures of a dome with the ground surface;while in the space,they take a form of conical sheet dipping inside,and the top of the cone directs at the dynamic field of magma activity.2.The structural dome of volcano was subsiding in the course of periodic dynamic equilibrium between the gravity of the dome itself and the internal pressure of magma,leading to form a volcano-structural depression and semi-loop buried dykes dipping outside.They are distributed on different level of erosion surface and occupy a common center with the concentric multi-loop fractures formed in the dome stage,but at an opposite dip.3.The dome mentioned above was subsiding by shearing along the conical tension fracture weakend plane resulting in the formation of the multi-loop and stepping graben-structures of which the structural lines are approximately consistent with the isopotential lines of different level given by the volcanic formations decreasing progressively from the center towards the periphery of the dome.