The　band　gaps　of　phononic　crystal　(PC)　composed　of　(32.　4.3.4)　lattice　array　of　circular　steel　cylinders　in　water　have　been　investigated　both　theoretically　and　experimentally　with　the　plane　wave　expansion　method　and　the　ultrasonic　immersion　transmission　technique.　Compared　with　the　PC　consisting　of　square　array　of　circular　steel　cylinders　in　water　at　the　same　radius　and　distance　between　the　adjacent　steels　cylinders,　the　(32.　4.3.4)　lattice　PC　may　open　the　two　band　gaps　in　the　range　of　higher　frequency.　The　transmission　spectra　of　different　layers　of　(32.　4.3.4)　lattice　PC　were　measured　experimentally　along　the　Γ-X　and　Γ-M　directions　of　first　irreducible　Brillouin　zone.　The　relations　of　band　gaps　stability　and　layers　can　be　discussed　in　detail.　This　is　better　advantage　of　design　for　the　finite-sized　isolating　noise　materials.　A　good　agreement　between　the　frequency　range　of　transmission　spectra　of　acoustic　waves　for　this　crystal　and　theoretical　predict　with　plane　wave　expansion　method　is　observed.