This paper introduces mechanical design, modeling and analysis of a miniature throw-able robot with transformation capacity. The robot could keep in spherical shape for overall protection during throwing, and transform to a regular two-wheeled mobile robot with a foldable tail as a third point support. The robot also equips a servo-system to adjust pitch angle of the camera which facilitates robot operation. In the paper, transformation principle and related calculation are presented, and parameters of the foldable tail are discussed about respective influences on obstacle performance. In addition, servo-system of the robot camera is also modeled and analyzed. Both simulations and experiments have proved effectiveness of the robot design and correctness of related analysis.