In this paper, we try to calculate precipitation in Miyake Island, Japan. In order to know the temporal and spatial variations of precipitation, we have set 15 rain gauges randomly in the island to collect the monthly precipitation data since June 1994. It is found that the precipitation is very dierent from point to point. First, we used statistical methods to get the correlations between the monthly precipitation at our survey points and that at the weather station. Next, regression analyses were used to establish formulae to calculate precipitation as a function of altitude, aspect of the geomorphological surface and wind direction. Based on these results, distributions of monthly and yearly precipitation and d 18 O over the island were assessed. The results show that landscape patterns strongly inΒ―uence precipitation distribution over the island, with the highest precipitation being found on the windward side, about 400Β±600 m above sea level. Even at places at the same altitude, the precipitation was dierent because of the aspect of the landscape. At the same time, altitude eects for d 18 O on both the windward and leeward sides were Γ0Γ10%a100 m and Γ0Γ15%a100 m, respectively. Comparing with the distribution of precipitation distribution, it was also found that d 18 O for the windward and leeward sides was dierent from that for precipitation, which means that both topographical eects must be considered separately.