Background: In recent years, more and more medical robots have formally stepped into clinical applications and are gradually being accepted by patients. Magnetic resonance image (MRI)-guided breast intervention robot is the most advanced technology for breast cancer treatment. Still, the very limited working space within the MRI scanner restricts the development of breast intervention robots. Objective: In this paper, a compact breast biopsy robot in MRI environment is proposed based on TRIZ theory. Methods: The structure of the robot is optimized by using the curvilinear principle and the asymmetry principle of TRIZ theory to obtain a modified cartesian coordinates robot for breast biopsy. The coordinate systems of the robot are established using D-H method. Next, 3D visualization simulation of the robot is performed by SimMechanics of MATLAB, and then kinematic simulation and workspace simulation analysis are carried out. Results: The simulation results show that motion space of the end effector of the robot meets the requirements of breast intervention surgery, and the robot structure is simple and effective. Conclusion: In this paper, a compact breast biopsy robot in MRI environment is proposed. Through the Simulink module of MATLAB to analyze its workspace, it is obtained that its working range is 250mm × 300mm × 200mm, which can cover any position in breast tissue. At the same time, the simulation results of the workspace also show that the structure optimization of the breast biopsy robot based on TRIZ theory is reasonable.