This paper addresses a modular designed biomimetic amphibious robot. Given the variable joint number and master-slave wheel-driving mechanism, a steering approach for turning control on land is proposed for a modular robot with arbitrary joint number, and a minimum turning radius is obtained. The ADAMS-based kinematics modeling as well as corresponding simulations are conducted and outlined for the multi-joint turning control of the amphibious robot. The balance analysis further verifies the steering approach to the amphibious robotic prototype. The experimental results demonstrate that the proposed steering method is effective and satisfies robot's operation requirements on land.