This workshop is motivated by the upcoming needs of the 20-T level accelerator magnets for recently proposed circular pp colliders, ie., the Super proton proton Collider (SppC) and the Future Circular Collider (FCC). The purpose of this workshop is to review the present related technologies on high field accelerator magnets, with special emphasis on the high Jc Nb3Sn and HTS conductors, the design study of the 20-T accelerator magnets and the fabrication methods of the high field coils and magnets. The R&D roadmap for the next years and possible collaborations between labs will be discussed, to make sure we are able to realize the 20-T dipole and quadrupole magnets in time. Any institutes or companies working on these issues are welcome to participate in this workshop, to give presentations, exchange information and to have fruitful discussions.