The static characters of the in pump style gas lubricated spiral grooved thrust bearing such as pressure field and loading capacity was presented by computational fluid dynamic numerical method. Designing parameters including ridge groove width ratio, gas film thickness and rotating speed of the bearing influenced on the loading capacity of the bearing were analyzed. The numerical results indicate that the pressure at the inner part of the groove around the sealing area is above the average pressure in the gas film which forms a large portion of the loading capacity. The loading capacity is improved with the increase of speed and the decrease of gas film thickness. There exists a maximal loading capacity with the ridge to groove ratio in the range of 06~08 and the optimal groove depth to film thickness ratio which agrees well with the designing experiences.