Before the opening of the traditional Silk Road, exchanges had already taken place between China and its western areas, as shown by a large number of unearthed cultural relics. Northwest China is the cradle of the traditional Silk Road; therefore, studying the cultural relics unearthed from this area is of great significance for promoting cultural relic protection and contemporary social construction in the context of the Belt and Road Initiative. In recent years, some tinned bronze belts dating back to the later Spring and Autumn Period (770-476 B.C.) and the early Warring States Period (475-221 B.C.) have been excavated from Shaanxi and Gansu Provinces and the Ningxia Hui Autonomous Region, China. The geometric patterns engraved on the surfaces of these belts are fairly clear even after tinning. In this study, 3D stereoscopic microscope, metallurgical microscope and scanning electron microscope with energy dispersive spectrometer (SEM-EDS) were used to examine these objects. Two basic techniques of engraving patterns on the surfaces of tinned bronze were recognized:the V-shaped chisels used for making short straight, long straight and curve lines, and the wheel-cutting used for forming long wide lines. The latter pattern, supposedly made using a steel-wheel, shows the earlier evidence for the formation of long wide lines on bronze surface.