Low power and high switching ratio are the development direction of the next generation of resistive random access memory (RRAM). Previous techniques could not increase the switching ratio while reducing the SET power. Here, we report a method to fabricate low-power and high-switching-ratio RRAM by adjusting the interstice radius (r g) between the van der Waals (vdW) layers of transitional-metal dichalcogenides (TMDs), which simultaneously increases the switching ratio and reduces the SET power. The SET voltage, SET power, switching ratio and endurance of the device are strongly correlated with r g. When the ratio of r g to the radius of the metal ions that form the conductive filaments (r g/r Ag+ ) is near 1, the SET voltage and SET power vertically decrease while the switching ratio vertically rises with increasing r g/r Ag+ . For the fabricated Ag/SnS2/poly­(methyl methacrylate)/Cu RRAM with an r g/r Ag+ of 1.04, the SET voltage, SET power and switching ratio are 0.14 V, 10–10 W and 106, respectively. After 104 switching cycles and a 104 s retention time, the switching ratio of the device can still be stable above 106. Bending has no influence on the performance of the device when the bending radius is not <2 mm.