A present disclosure relates to a system for automatic design and manufacturing of 3D printing units and 3D products. The system is configured to obtain specification of a target structure corresponding to a 3D product; automatically determine a design and a printing path of a 3D printing unit based on the specification of the target structure, wherein the 3D printing unit is a micronozzle unit configured to print the target structure of the 3D product; automatically determine a manufacturing procedure to print the 3D printing unit based on the specification of the target structure; and instruct a 3D printer to print the 3D printing unit according to the manufacturing procedure and the printing path of the 3D printing unit.