By using DFT method, we stitch monolayer MoS2 nanoflakes with different manners to tune the behaviors. The stability of these structures is identified by molecular dynamics simulations. The effect of chemical modification is also given and assessed by the calculated edge adsorption energy. It is found that the electronic structures can be manipulated from semiconducting to metallic properties by different edge modifications. The prototypes can also be constructed into three-terminal FET which owns smaller value of subthreshold swing S and the considerable transconductance G comparable to that of experiments. More importantly, we utilize the spin-transport properties to achieve a kind of voltage-driven spintronic logic gates. We control the spin transport with the electric field only and find the model can function in all base 'AND', 'OR', 'NOT' logic operations under specific combinations of the gate bias. The advantages of monolayer MoS2 nanoflakes are thus expected.