To meet the requirements of regional atmosphere environment management, the concept of air resource was put forward. Then estimation and assessment methods were presented. A case study was conducted for the domain of the west of Taiwan Strait. Based on the analysis of climate characteristics and various weather systems associated with high levels of air pollution occurring in this area, both the regional and local meteorological fields were simulated with the Weather Research and Forecasting (WRF) model. The key factors that affected air resource significantly were selected from the meteorological fields and turbulence parameters. They acted as evaluating indicators of regional air resource. Each of the factors was classified and then graded to determine the weighted coefficient. The total scores of air resource in west Strait were estimated from the weighted sum of the respective factor scores. The levels of air resource were determined subsequently. Finally, spatial distribution of the overall scores and the levels of air resource were obtained. It showed that the air resource over the Strait was of the top grade (5) with the score 18. The grades in the rest were of 2 to 4 with the scores 14 to 18. In general, the air resource in coastal area was most abundant, in inland flat less and in mountainous area the least, showing an inhomogeneous pattern. The results indicated that the method proposed in this paper was a reasonable solution to assess regional air resource. There will be a great application prospect for regulation and management of atmosphere environment.