The small watershed is the complexed gigantic system out of the sub-systems of ecology , economy and sociey,the harness of the small watershe is in fact a coordinating to the three sub一systems. Analysing the nature and characters of small watershed and its harness from the point of philosorphy it is thought that not only the linear,inner,standard,balance,gradual advancement,stable,transparent , definition,precise and qualitative nature should be studied ,but also the composition ,structure and function as well as the evolving process and the factors affecting the benefit from harness of small watershed be examined,thus the opposite of the small watershed and its harness be understood,which would provide correct methodology to recognize the factors of small watershed and their relations from each other,to master the laws of development of the whole system and formulate reasonable plan and strategy to harness small watershed.