The self-reconfigurable modular robot consists of many identical modules. By connecting to/disconnecting from other modules, the whole structure of the robot can transform into arbitrary other configurations. First, the lattice-type self-reconfigurable modular robot is proposed and its disconnected/connected mechanism is analyzed, which can finish self-morphing action. Second, the basic configuration of the module is analyzed with the eigenvector matrix. The motion rules are proposed. Third, the possible motion space is described with the geometric feature of modules which is effective for performing the self-morphing process. Then, the selfmorphing motion process is described with the driving function and the adjacency matrix which is useful to solve the computation problem and optimize the motion paths of the robot during the self-reconfigurable morphing process. Final, an experiment of three-module motion and a simulation of multi-module's self-morphing process are shown to prove that the above analyses are effective.