High rate of charge carrier recombination is a critical factor limiting the photocatalytic activity of g-C3N4. In this contribution, we demonstrate that this issue can be alleviated by constructing a plasmonic photocatalyst with tailored plasmonic-metal nanostructures, i.e., core–shell-typed Ag@SiO2 nanoparticles. Compared with pure g-C3N4, the photocatalytic hydrogen production activity was enhanced by 63% for Ag@SiO2/g-C3N4. As analysis from the photoluminescence results, the enhancement could be attributed to that plasmonic nanostructures favored the separation of electron–hole pairs in the semiconductor due to localized surface plasmons resonance effect. It was found that the silica shell between the Ag nanoparticles and g-C3N4 was essential for the better photocatalytic activity of Ag@SiO2/g-C3N4 than that of Ag/g-C3N4 by limiting the energy-loss Förster energy transfer process.