Smart skin seamlessly integrates a heterogeneous multifunctional circuit system on the surface of the load-bearing structure of an aircraft, serving as an enabling technology for achieving the“ Fly-by-Feel” capability in future variant aircraft. The smart skin of the aircraft involves various functional modules, including multifunctional  distributed sensing systems, conformal antennas, frequency-selective surfaces, and anti/de-icing. This integration enhances the aircraft’s situational awareness and promotes the development of lightweight structures, and the technical key is the fabrication of heterogeneous multilayer circuits on the intricate 3D surfaces. In addressing the manufacturing challenges associated with the multifunctional circuits of smart skin, this paper provides a detailed analysis of the difficulties encountered in the manufacturing of different types of curved functional units. Additionally, it compares and elucidates manufacturing technologies applicable to diverse structural types, encompassing conformal printing, via-hole interconnection, curved surface attach, and thin-film fabrication. Finally, the paper summarizes and forecasts the challenges and potential solutions confronting the manufacturing technology for heterogeneous multilayer circuits in smart skin, offering valuable insights for the breakthrough of next-generation aircraft smart skin manufacturing processes.