Abstract: A new type of combined seal system with ferromagnetic flow and gas along cylindrical spiral groove is proposed in this paper. Based on the study of the two seals respectively, experiments on the combined seal system are carried out. Results show that the seal system has enough seal ability to fulfil the speed limit from zero to designed value. At high speed, gas seal can prevent the splash of ferromagnetic flow effectively and restore the seal ability when the seal film of ferromagnetic flow breaks up, so it is a pollution-free and reliable seal. It is also revealed that the combined seal is characterized by being adapted to diverse seal occasion by adjusting structural design parameters. The performances are beyond the reach of other kind of non-contact seals.