Ammonia　decomposition　is　a　structure-sensitive　reaction,　so　the　difference　in　structure　of　Ammonia　decomposition　is　a　structure-sensitive　reaction,　so　the　difference　in　structure　of　similar　catalysts　may　have　a　great　impact　on　the　catalytic　performance　of　ammonia　decomposition　reaction.　However,　it　is　not　clear　which　structural　properties　can　play　a　role　in　ammonia　decomposition　reaction　and　the　degree　of　influence　on　catalytic　performance.　To　explore　this　question,　ammonia　evaporation-hydrothermal　(AEH),　impregnation　(IM),　and　evaporation-induced　self-assembly　(EISA)　methods　were　used　to　synthesize　Ni/SiO2　catalysts　to　obtain　carbon-free　hydrogen　from　catalyzing　NH3　decomposition　reaction.　Among　the　three,　the　Ni/SiO2　catalyst　synthesized　via　ammonia　evaporation-hydrothermal　method　is　the　smallest　in　terms　of　Ni　nanoparticles　(similar　to　3.0　nm)　and　the　strongest　Ni-SiO2　interaction.　For　ammonia　decomposition,　it　is　the　highest　in　activity　and　thermal　stability.　The　NH3　conversion　at　650　degrees　C　and　30　000　mL　g(cat)(-1)h(-1)　(GHSV)　over　Ni/SiO2-AEH　was　close　to　90　%　and　remained　stable　in　an　evaluation　period　of　60　h.