Provided is a 3D printing apparatus combining plasma melting and multi-axis milling processes based on Internet signal transmission. The 3D printing apparatus comprises a worktable (10), a numerical control revolving table (20), a plasma overlay welding machine (30), a multi-axis milling mechanism (40) and a control system (50). The worktable (10) is provided with a panel (11), and the numerical control revolving table (20) is provided on the panel (11). The plasma overlay welding machine (30) comprises a plasma overlay welding power control box (31) and a plasma overlay welding head mechanical mechanism (32). The multi-axis milling mechanism (40) is provided above the worktable (10). The control system (50) is externally connected to the Internet, and 3D drawing data of a product required by a client is transmitted to the control system (50) through the Internet. The control system (50) controls the numerical control revolving table (20), the plasma overlay welding machine (30) and the multi-axis milling mec
