The　band　structure　(BS)　and　the　transmission　loss　(TL)　of　a　two-dimensional　(2D)　solid/liquid　phononic　crystal　(PnC),　which　is　composed　of　cylinder　water　immersed　in　steel　matrix,　are　investigated　by　the　finite　element　method　(FEM).　Meanwhile　the　effects　of　various　factors　on　the　BS　of　two-dimensional　solid/liquid　phononic　crystals　(PnCs)　are　analyzed.　Unlike　other　literature,　this　paper　first　compares　the　advantages　of　steel/water　phonon　crystals　over　other　solid/rope　crystals.　The　effects　of　lattice　constant,　filling　rate　and　the　number　of　sides　of　regular　polygon　on　the　band　gap　characteristics　of　2-D　steel/water　phonon　crystals　are　investigated.　At　the　same　time,　it　is　found　that　the　shape　of　scatterer　has　little　influence　on　the　band　gap,　which　is　beneficial　to　the　design　of　simple　scatterer　shape.　It　is　revealed　that　the　model　has　the　advantages　of　forming　band　gaps　at　low　frequency　and　larger　bandwidth　comparing　with　other　structures.　Moreover,　the　results　show　that　the　band　gaps　(BGs)　move　to　low　frequency　as　the　lattice　constant　increase.　Meanwhile,　there　is　a　linear　relationship　between　the　change　of　the　first　complete　BG　and　the　lattice　constant　and　the　first　complete　BG　bandwidth　decreases　gradually　with　the　increase　of　the　filling　rate　of　the　scatterer.　However,　the　shape　of　the　scatterer　has　little　effect　on　the　BGs.　The　designed　model　will　bring　convenience　to　low-frequency　vibration　isolation　and　noise　reduction.　The　investigation　in　this　paper　can　be　expected　to　utilize　in　the　design　of　noise　insulators　or　vibration　isolation　facility　in　the　large　engineering　projects.　©　2022,　The　Author(s),　under　exclusive　license　to　Springer　Nature　Singapore　Pte　Ltd.