Abstract: This paper propesed that one may use phenology method for climatic investigation in a small area,and discussed systematically the method and steps for inves-tigation.Finally,according to the practical condition of China,the author recommendsd the application of phenology method in climatic investigation of mountain area and county climatic regionalization.The full text is divided into three parts:1.Indicative phenology phenomenon and analysis of the climatic elementsindicated.The phenology phenomena indicating each season are classified and numerous temperature indices of cold damage for tropical belt and subtropical belt plants insouthern China are cited.2.procedures for calculating climate in small area bv phenology method andthe phenology phenomen on investigation method.Procedures:(1)Compare and analyze phenology data and climate data of same location,establish regression equation between them for stand-by purpose.(2)Collect and find indicative phenology phenomenon and determine corresponding climatic indices for stand-by purpose.(3)Determine climatic analysis items for certain location and then determine the scope and method of phenology investigation.(4)Organize phenology observation and investigation.(5)Sort out and analyze the phenology investigation data and convert the min to climatic element values.Finally,make out climatic figure and climatic regi-onalizition figure,and write out a summarizing report.Investigaiton methods of phenology data:Fixed point observation method and moving observation mathod.3.Illustrations with examples concerning some applications of phenology inmountain area climatic investigation and county climatic regionalizition of China.