Among the heavy metals, arsenic is known as a carcinogen and its high concentrations in the ecosystem can be a major concern for public health and the environment. The aim of this study was to evaluate the ecological and human health risks of arsenic in the Central part of Hamedan-Bahar Plain. For this purpose, arsenic concentration in 94 points of groundwater, 49 points of surface soil and 30 points of crops in the study area were analyzed and evaluated. To determine the spatial distribution of arsenic, different geostatistical methods were used. For determining spatial distribution of arsenic in the soil and groundwater, RBF method by multiquadric model was used. Contamination probability map for soil and groundwater was developed using indicator and probability kriging models. Areas where soil and groundwater contamination is high were matched with agricultural land especially the potato fields, which can be due to excessive useing of chemical fertilizers and poultry in these areas. In order to calculating health risk and determining the carcinogenic and non-carcinogenic risk of arsenic, different routes of exposure were evaluated and daily intake was calculated in four age and sex groups. In the next step, risk assessment map of arsenic contamination in the region was developed using fuzzy and WLC methods.Soil physico-chemical parameters (clay, organic matter and pH), soil and groundwater contamination probability map and land use map as the input of these two methods were selected. Keywords: Arsenic, Hamedan-Bahar plain, Spatial distribution, Health risk, Fuzzy, WLC