Abstarct: Geostatistical techniques were used to describe the spatial distribution of weeds, under different weed management conditions and its effect on wheat (Triticum aestivum L.) yield in four winter wheat fields over the course of one growing season (2010- 2011), located at College of Agriculture, Shahrood University of Technology. The treatments consisted of four fields: First field:(without nitrogen and herbicide application), second field (175 kg/ha nitrogen fertilizer and without herbicide), third field (175 kg/ha nitrogen fertilizer and broadcast application of 2,4-D+MCPA) and fourth field (175 kg/ha nitrogen fertilizer and patchy application of 2,4-D+MCPA). In three sampling stages weeds seedling were identified and counted at 135 points of the first field and fourth field (patchy treatment) and 120 points of the second and third fields baxsed on a 4×4 m grid. leaf chlorophyll content of wheat, weed biomass dry weight, wheat biomass dry weight and wheat yield were determined at the same places of weeds. The result indicated the application of herbicide was a useful factor to reducing weed seedling. In patchy weed control treatment, herbicide use was reduced by 55.5 percent than broadcast application. Semi-variogram analysis indicated that weed population in during the three stages of sampling and weed biomass dry weight had a patchy distribution pattern in all of fields. This study indicated that patchy distribution of weeds can cause spatial heterogeneity in leaf chlorophyll content of wheat, crop biomass production and yield of crops on the fields. Cross-semivariograms analysis showed strong spatial continuity (90%) and low spatial continuity (39%) between leaf chlorophyll content of wheat and weed density patterns on the second field and on the third field respectively. But on the first field high spatial dependence (95%) and on the fourth field moderate spatial dependence (62.24%) were observed between inverse density of weed population and leaf chlorophyll content of wheat. Cross-semivariograms analysis showed strong (74/15%) and moderate (54/05%) spatial continuity between weeds biomass dry weight and inverse wheat yield and between weeds biomass dry weight and inverse wheat biomass dry weight in the second field respectively. Cross-semivariograms analysis showed strong (87%) spatial correlation between total weeds population and inverse wheat biomass dry weight and also between total weeds population and inverse wheat yeild in the third field but in the other field did not show spatial correlation. As a result, patchy weed distribution and their spatial variability during the growing seasen can cause spatial heterogenity in crop yield on the fields.