When designing the 3D model for 3D printing, often neglect some physical factors of model itself, which will cause a variety of problems, such as surface-rupturing, out-off-balancing, some force loads problems and so on. These problems all can be solved by the 3D model optimization design. Currently, the 3D model optimization includes 3 ways, which are mechanical-characteristic-oriented analysis optimization, supportive structure optimization of model-printable-oriented and model segmentation optimization of model-printable-oriented. The methods, technologies and features of the model optimizations for 3D printing from the above 3 ways are introduced by combining with the relevant references and author researches. Based on the analyses and researches, put forward the future development trends and directions of model optimizations for 3D printing. The research results can provide reference for related 3D printing technology research.