It should be considered in natural draft counter-flow cooling tower (NDCCT) design that the natural wind may reduce the efficiency of cooling tower. In this paper, pressure flume model has been used to investigate the influence of natural wind on the resistance coefficient at the air inlet of NDCCT. Laboratory experimental results show that the resistance coefficient at the air inlet increases with an increase in the natural wind speed. This study presents an estimation formula of resistance coefficient at the air inlet for variable natural wind speeds, which provides references for NDCCT design.