Abstarct: Topographic condition could be considered as one of the most vital factors for soil formation that may substantially affect the local soil properties. The present study was done in Kalpoosh area, Shahrood, aimed to assess the influence of slope position and aspect on soil structure stability and selected physico-chemical soil properties. For this purpose, a total of 30 surface soil samples (0-30 cm) at two northern and southern aspects and five slope positions, consisting of summit, shoulder, back-slope, foot-slope and toe-slope were collected. All soil samples were analyzed for selected soil properties, including soil pH, electrical conductivity (EC), organic matter (OM), available phosphorus (P), carbonate calcium content, soil texture, dispersible clay content, particle and bulk denstisties, soil porosity, mean weighting and geometric diameter of soil aggregates and distribution of OM and phosphorus in different-sized soil aggregates using both wet and dry sieve methods. The results indicated that due to early cool and snow cover in the lands located on northern slope in Kalpoosh area, soil OM content (2.23%) and structure stability index (1.98 Mm) were lower compared to the soils located on southern slope. Comparison of OM content in soils located on different soil positions revealed the highest content of this parameter in back-slope (4.79%), which may be arisen out of the relatively good density of plants in this part because of the gentle slopes. Studying the distribution of OM and P in different-sized soil aggregates using wet and dry sieve approaches showed that the highest content of these soil quality indicators were mainly found in smaller soil aggregates when the wet sieve method was used; whereas, in terms of dry sieve method, larger soil aggregates contained more OM and P.