A series of polyoxometalates (POMs)-based coordination polymers, namely, {[Cu(2,3-Me(2)pz)(2,5-Me(2)pz)(0.5)](4)-(SiW12O40)(2,5-Me(2)pz)}(n) (2,3-Me(2)pz) =2,3-dimethylpyrazine; 2,5-Me(2)pz = 2,5-dimethylpyrazine; 1), {[Cu-2(4,4'-bipy) (4)(H2O)(4)](SiW12O40)(H2O)(18)}(n) (4,4'-bipy) 4,4'-bipyridine; 2), {[Cu(2-Mepz)(1.5)](3)(PMo12O40)(H2O)(3.5)}(n) (2-Mepz) 2-methylpyrazine; 3), {[Ag(2,3-Me(2)pz)(1.5)](4)(SiW12O40)}(n) (4), {[Cu(pz)(1.5)](4)(SiW12O40)(H2O)(3)}(n) (pz = pyrazine; 5), {[Cu(2,3-Me(2)pz)(1.5)](4)(SiW12O40)}(n) (6), {[Cu(4,4'-bipy)(1.75)](4)(SiW12O40)(H2O) 2}(n) (7), and {[Cu-2(4,4'-bipy)(4)(H2O)(4)](SiW12O40)(4,4'-bipy)(2)(H2O)(4)}(n) (8), were synthesized through direct incorporation between POMs and the voids of the 2D network. Crystal structural analysis reveals that the relationship between the size of the void of the 2D network and that of POMs is of key importance for successful synthesis of POMs-based open metal-organic frameworks. Guest replacement shows that the pore size of the framework constructed through direct incorporation between POMs and the voids of the 2D network is very sensitive to guest molecules.