The reverse S-shaped fold-and-thrust belts in the northern Qaidam Basin were interpreted as a result of lateral traction by sinistral strike slip of the Altyn fault in the north edge of the basin. However, the deformation features of the Qaidam Basin indicated that the area influenced by strike slipping of the Altyn fault was very narrow. To further study the mechanism of the reverse S-shaped fold-and-thrust belts, a set of sandbox models of arcuate boundaries with different substrate were designed according to the actual geological conditions. The experimental results showed that the strikes and structural patterns of fold-and-thrust belts were mainly controlled by the boundary geometry of rigid blocks and partially by the mechanical properties of substrates. Based on analyses of the experiments and deformation characteristics of the northern Qaidam Basin, it was proposed that the reverse S-shaped fold-and-thrust belts there could be simply interpreted as the “combination effect of arcuate boundaries of rigid blocks”, namely, 1)the Lenghu reverse S-shaped fold-and-thrust belt being a combination effect of arcuate block boundaries of the Saishiteng Mountains and the Kunteyi Sag; 2)the Eboliang reverse S-shaped fold-and-thrust belt being a combination effect of arcuate block boundaries of the Kunteyi Sag and Yiliping Sag; 3)the fold-and-thrust belt, along southwest edge of the Yiliping Sag and with a reverse traction relation to sinistral strike slipping of the Altyn, being related to the southwestward curved boundary of the sag.