Abstract: The study, taking systemic functional linguisticsas a basis, aims to analyze usage features of participant nominal group from the type and the pre-modifier perspectives. The result that many transcategorization and technical terms are adopted shows abstractness, technicality and complexity of academic texts. The statistical result of a few compress proves that nominalized groups are mainly considered as references of abstract entities but seldom as the packing of a clause and information development resource. The result that dectic covers a majority in pre-modifiers, but less epithet and lest classifier shows the decrease of objectivity and abstractness, hence dynamic andinstantial features of academic texts.