Abstarct: Groundwater resources are of the main sources for drinking water supply, agriculture and industry usage in the South West of Bukan plain. In this study, factors affecting the quality of groundwater resource of Bukan plain have been investigated by collecting 17 groundwater samples. Major ions and TDS concentrations, were determined by standard methods, and potentially toxic elements concentrations by ICP-OES. The mean concentrations of calcium, magnesium, sodium and potassium in the water samples, were 68, 28, 28, and 1 mg per liter respectively. The average concentrations of bicarbonate, sulfate and chloride were 310, 42 and 41 mg/l respectively. The average concentrations of nitrate and phosphate, were 1.2 and 0.3 mg/l respectively. The average concentrations of lead, cadmium, zinc, molybdenum, copper, arsenic, chromium, selenium, boron and manganese, were 22, 13, 158, 49, 6, 4, 21, 30, 218 and 17 µg/l, respectively. baxsed on the results of this study, groundwater resources of Bukan plain are of bicarbonate water type and calcic facies. Saturation Index values also show that groundwater is in equilibrium with carbonate minerals (calcite, dolomite and aragonite). Gibb’s diagram reveal taht nearly all samples are plotted in the rock dominant zone. Ions ratios show that carbonate dissolution is the dominant process in the aquifer. Groundwater resource of Bukan plain has a relatively low concentrations of major ions and high concentrations of the potentially toxic elements compared to the standards of the World Health Organization. Salinity index values reveal that almost all of the water samples show no sodium problem. Wilcox diagram also shows that most of the water samples are in the suitable category. Water quality index for the samples of Bukan plain show that groundwater sample fall with in good to excellent range and pose no problem for drinking. Langelier index, shows that most of the water samples have corrosive and crvestation properties. This property indicate that groundwater is not suitable for various industries. Concentrations of potentially toxic elements in the groundwater resource of Bukan plain was (except for Mn) higher than the concentrations in freshwater. heavy mextal concentrations in groundwater resource of Bukan plain has relatively high concentrations compared to the World Health Organization standards. Some mextals such as cadmium, lead and selenium values are higher than World Health Organization standards for drinking. Groundwater resource of Bukan plain for agricultural purposes are appropriate, but for industrial and drinking purposes (due to high concentrations of Lead, Cadmium and Selenium) are inappropriate. In this study, for some elements such as Lead, Zinc, Cadmium, Arsenic and Molybdenum, natural (black shales) and domestic wastewater origin are proposed. fertilizers and Sewage are probable source for selenium, Chromium and Boron in the groundwater resources of this plain.