This paper introduces an noval autonomous mobile robot, IOMT, designed for indoor and outdoor multi-terrain environments, with a particular focus on stair-climbing capabilities. The robot features a four-wheel independent drive and steering system (4WID-4WIS), allowing it to maintain high maneuverability on smooth surfaces. Furthermore, based on reducing the complexity of the control, the IOMT addresses the challenges associated with stair climbing by controlling the stable pitch angle, effectively reducing the impact of stairs on the robot's posture, such as the pitch angle minimized to an angle smaller than the inclination of the stairs. The design also incorporates a special mechanism that reduces energy consumption through its worm gear system with self-locking characteristics, and combines steering with shock absorption to simplify both the mechanism complexity. This paper not only briefly proposes a stair climbing strategy for the IOMT, but also explores the impact of various design parameters on the robot pitch angle, ultimately validating the feasibility of the design for the stair climbing ability.