The Loess Plateau is gully and hilly with serious soil erosion and thus a thorough study on the landscape development and erosion process with the scope of small watershed is of vital importance for ecological restoration of this region. As a macroscopic landscape analyzing method, hypsometric integral could be used for a comprehensive analysis on the development stages and process of small watersheds. Nevertheless, this method could produce distinct scale-effect and consequently an in-depth recognition on the finest analysis scale is a basis for properly understanding the characteristics and development of the watershed. This paper, with small watershed in Loess Plateau as the object of study, elaborately analyzes the scale-effect of hypsometric integral from the perspectives of analysis scale, statistical scale and regional scale based on 5-meter-resolution DEMs. The results show that, with the increase of hypsometric series under analytical scale, the integral value decreases sharply to close to the true value, yet the decreasing range narrows greatly and finally hypsometric curve becomes more accurate. As DEM resolution in statistical scale rises, hypsometric integral value basically remains unchanged, and this value is closely related to the other two land surface parameters, depth of surface cutting and relief height of landscape. Moreover, when considering regional scale in the same landscape, the smaller the analytical area is, the greater the integral value difference will present. At last, the integral value tends to remain steady when analytical area reaches a certain degree. This paper lays a foundation for further analysis of watershed characteristics.