To effectively reveal scale effect of soil attributes and provide information for sampling design, the spatial variability response rules of soil organic matter and total nitrogen to sampling grain size were identified by spatial autocorrelation, semi-variogram and fractal dimension in Loess Plateau, China. The results showed that the average content of SOM and STN were 14.79 g/kg and 0.78g/kg, respectively. With the sampling grain size increasing, the coefficient of variation of SOM had basically not changed, but that of STN showed a gradually elevated trend. In addition, the spatial autocorrelation of SOM and STN was weakened and their spatial variability from random factors became much stronger. Meanwhile, the relationship between spatial variability and sampling grain size was not linear, but a reverse “U” type changing trend. The spatial distribution of SOM and STN concentration exhibited higher in the north and lower in the south of study area. SOM content was at the mid-low level, but STN content was under the normal level which led to much more nitrogen needed in the future. 