This paper presents a novel field robot JL-I based on a reconfigurable concept for urban search and rescue applications. The robot consists of three identical modules; each module is an entire robotic system that can perform distributed activities. It features three-degrees-of-freedom (DOF) active joints actuated by serial and parallel mechanisms for changing shape and flexible docking mechanism. The docking mechanism enables adjacent modules to connect or disconnect flexibly and automatically. DOF analysis, working space analysis and the kinematics of the 3D active joint between connected modules are studied thoroughly. In the end a series of successful tests confirm the principles and the robot's capabilities.