Based on the survey in the field and the analysis of field data,this paper has introduced the concepts of sand wave and its transportation,and discussed the classification principle and then suggested a clssification system of sand wave in alluvial stream. According to the classification,the sand wave in alluvial stream is divided into two grades.The first grade includes two kinds of sand wave and the second includes six.This paper gives respectively definition to each kind of sand wave,descripting its geometrical shape,formation,transportation and so forth,and emphasis to the differentiation,in the first and the second grade of sand wave.