Aiming at the problems of insufficient passing ability and flexibility of existing mobile robots in complex and narrow environment, a modular reconfigurable tracked robot is proposed inspired by the recombination deformation mechanism of amoebas. By simulating the rigid-flexible transition characteristics of amoeba cytoplasmic particles, a lockable track module based on the latching structure was designed by fusing the pitch and yaw joints. Multiple track modules were connected in series to form a closed-loop single chain to form the external structure of the robot. Under the drive of the internal flexible body, the track chain could realize continuous rolling. By successively adjusting the yaw joint angle of front track modules and locking them by the body head, while unlocking the rear track modules in turn by the body tail, the robot could actively change its geometric morphology during the forward process. Then, based on the position relationship between adjacent track modules described by the joint angles, the morphological matrix of the robot was obtained, and the kinematics model of the robot was established by the iterative analysis of the joint angle sequence. Finally, the morphological variation range of the robot was simulated and analyzed to accurately evaluate its motion flexibility, and its motion performance was verified by making a robot prototype and carrying out a series of test experiments. The results showed that the minimum turning radius of the robot was 17.7 cm, and the robot could flexibly avoid obstacles in narrow confined space by continuously changing the yaw direction. With the passive adaptation of pitch joints, the robot could traverse all kinds of rough terrain, thus verifying the flexibility and passing ability of the robot. The research results can provide new ideas for the bionic structure design of mobile robots.