The　characteristics　of　multi-point　defect　phononic　crystal　(PC)　composed　of　square　array　of　circular　steel　cylinders　in　water　are　investigated　experimentally　using　the　ultrasonic　immersion　transmission　technique.　The　band　structures　of　the　PCs　are　obtained　by　the　finite　element　method　with　9x9　supercell　approximation.　A　very　good　agreement　with　the　experimental　results,　numerical　transmission　data　and　eigenmode　frequencies　of　band　structures　is　observe.　Meanwhile　the　number　of　multi-point　defects　affects　the　localized　modes　of　cavities　and　propagation　characteristics,　and　the　eigenmodes　of　defects　show　the　symmetric　or　antisymmetric　modes　in　designing　the　new　type　of　acoustic　wave　devices.