Abstract: Aiming at the problem of most 3D printing light-weight filling structures cannot be self-supporting,resulting in the model cannot be printed and formed,and the additional support structure will cause the residual printing materials in the model cannot be discharged,a design method of self-supporting connectivity filling structure for 3D printing is proposed. Firstly, based on each layer of printed slices, the filling structure is constructed. Secondly, the self-supporting and connectivity of the filled structure are realized by adjusting the parameters to control the continuous periodic change of equilateral triangles in different layers. Finally, a G-code file that can be directly used for printing is generated according to the geometric information of each layer. Through printing models, drilling and pouring water and mechanical tests, the results show that the method can print the filling structure with different self-supporting angles and two connected regions, and the filling structure has good mechanical properties compared with the five typical filling structures.