Synaptic　devices　that　mimic　biological　synapses　are　considered　as　promising　candidates　for　brain‐inspired　devices,　offering　the　functionalities　in　neuromorphic　computing.　However,　modulation　of　emerging　optoelectronic　synaptic　devices　has　rarely　been　reported.　Herein,　a　semiconductive　ternary　hybrid　heterostructure　is　prepared　with　a　D‐D’‐A　configuration　by　introducing　polyoxometalate　(POM)　as　an　additional　electroactive　donor　(D’)　into　a　metalloviologen‐based　D‐A　framework.　The　obtained　material　features　an　unprecedented　porous　8‐connected　bcu‐net　that　accommodates　nanoscale　[α‐SiW12O40]4−　counterions,　displaying　uncommon　optoelectronic　responses.　Besides,　the　fabricated　synaptic　device　based　on　this　material　can　achieve　dual‐modulation　of　synaptic　plasticity　due　to　the　synergetic　effect　of　electron　reservoir　POM　and　photoinduced　electron　transfer.　And　it　can　successfully　simulate　learning　and　memory　processes　similar　to　those　in　biological　systems.　The　result　provides　a　facile　and　effective　strategy　to　customize　multi‐modality　artificial　synapses　in　the　field　of　crystal　engineering,　which　opens　a　new　direction　for　developing　high‐performance　neuromorphic　devices.