[en] The 1.5 GeV SPIN accelerator being constructed at JINR is a strong focusing synchrotron with an superconducting separated function magnet system. The magnet system comprises two supercells. Each of them has 12 regular FODO cells and a matched straight section. A cold part of the beam injection channel is also equipped with SC magnets, so the magnet system of the accelerator contains 52 SC dipoles and 64 quadrupoles with a 3t total weight. All the SC magnet are placed in a common helium cryostat of the boiling bath type. The external wall of the 4 m³ bath is made of the 2.0 mm stainless steel sheet and the internal one is formed by the 0.5 mm vacuum chamber walls. The cryostat repearting the magnet system periodicity is holded by 42 supports made in the form of a cylindrical labyrinth. For thermal insulation of the 65 m total length cryostat only the 50-layer superinsulation and a vacuum case are used, so the expected cryostat heat load is approximately 400 W. The cryostat is connected with the 1600 W refrigerator by means of a 70 m helium pipe