This paper deals with a newly designed spiral-groove thrust bearing, with a slit seal around it. By the approximate theory of spiral-groove bearing, this new type bearing is analysed. As a result the formulas for calculating load capacity and stiffness of this bearing are given. In order to prove that the load capacity and stiffness of this bearing is much larger than that of conventional spiral-groove thrust bearing, an example is offered. This type of spiral-groove thrust bearing presents a new possibility to improve the performances of gas lubricated thrust bearings.