Abstract: This paper introduces a new type buoyancy testing instrument and its components,operating principle,data collection and processing by computer and testing results in respect of its accuracy,stability and sensitivity.The instrument is composed of the weigh sensor in form of electric resistance strain gage,weigh digital display instrument and computer data processing software.It adopts overhang buoyancy testing design ways,which can collect buoyancy signals at real time on long time basis and record the changing processes of buoyancy.The instrument′s relative error is less than 3%;sensitivity reaches 0.1 N,so the instrument takes on very high stability.The instrument can meet different testing requirements of various floatation materials.At the same time,it can also apply to high precision requirements in scientific research,for instance,it can analyze influencing factors of buoyancy decline etc.