Abstarct: There are a number of methods that have been used for identification and separation of the geochemical anomalies from background. In the current research, Trend surface method was applied on multivariation geochemical index to separate mineralized zone from background area. A case study involving the analysis of stream sediment geochemistry data from an area in the south eastern of Gonabad, located in the north eastern of Iran was considered in this research. Single and multi-variant statistical analysis methods have been used to recognize the most effective geochemical parameters. Elements of lead, zinc, gold, silver, copper, cadmium, arsenic, bismuth, antimony, molybdenum, barium, tin, tungsten, mercury, manganese and iron were introduced baxsed on those methods. Mineralized elements (gold, copper, silver, lead and zinc) in the study area were identified, which might be introduced a polymextal mineralization zone. The spatial geochemical maps shown the most important anomalous elements in the northern part of the study area. To obtain a baxse map for the next step of investigation, the anomaly areas of the spatial geochemical map of elements with together, the distribution of important heavy minerals and the high mineralized rock samples from check anomaly samples were ploted on the same map. The mineralized areas were focused in the northern part of the baxse map. Correlation analysis, clustering and factor analysis were done on the anomalous data, a data set of 50 samples (25 anomal and 25 background samples). The elements of copper, gold, zinc, lead and silver were introduced as mineralized factor, which might be formed as epithermal probably mineralization. A geochemical index of Au+Ag+Pb/Ti+Cr+Ga was introduced baxsed on evaluation of these samples and coformation by the baxse map. Finally, trend surface method was applied on this geochemical index and for the whole area. The residual anomaly-4 degree could clarify And separate the anomaly areas from the background. The trend surface is considered as single variant method but it was applied for a mult-elements geochemical index ratio.