The Gramme-Ring -winding high-speed permanent magnet generators (GHSPMG) are the most attractive candidates for use as the emergency power supply due to its inherent high efficiency and high power density. Studying the inter-turn short circuit (ITSC)multi-physics characteristics of GHSPMG is of great significance to improving fault tolerance and the reliability of emergency power supply. The existing literature only studies the ITSC fault of stacked winding motor, ignoring the ITSC fault characteristics of the GHSPMG. This paper proposes an analytical-finite element coupling method suitable for GHSPMG motors, and studies the electromagnetic, temperature, and vibration multi-physical fields after GHSPMG failure. Firstly, based on the special structure of the GHSPMG, an electromagnetic model considering the ITSC fault is established, and the impact of the ITSC fault on the air gap magnetic field distribution characteristics is analyzed. Secondly, based on Maxwell tensor method, the influence of post-fault short-circuit circulating current on electromagnetic vibration characteristics is studied. Then, a fluid-structure coupling model is established to compare the internal temperature characteristics between healthy and faulty states. The results show that the fault impact range of the GHSPMG is quite different from that of the stacked winding motor, and when an ITSC fault occurs in the winding, the loop current only affects the multi-physics characteristics of a single fault slot of GHSPMG instead of two slots of stacked winding motor. Finally, an experimental platform is built to verify the effectiveness of the theoretical analysis.