Magnons have unique properties, including long propagation length, and can exist in insulators. Magnon valve structures, which consist of two magnetic insulating layers, offer a promising approach for advanced magnetoresistive randomaccess memory (MRAM) technology and an alternative to the limitations of traditional electronic devices. In this study, we investigate a magnon valve structure that incorporates a platinum (Pt) spacer between two magnetic insulator layers, specifically yttrium iron garnet (Y3Fe5O12, YIG). Structural characterization of the YIG/Pt/YIG magnon valve was carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM), confirming the high-quality growth of the multilayer structure. The magnon valve behavior was assessed through vibrating sample magnetometry (VSM) and spin Seebeck effect (SSE) measurements. Our results demonstrate magnon valve behavior, which becomes apparent as the Pt spacer reaches a thickness sufficient to decouple the magnetization of the YIG layers. The magnon valve ratio of the magnon valve can be modulated, and clarity of the those states can be enhanced.