Abstract: Microfloras in continuous planting vegetable soils in semi-arid region at Tianjin were studied． In this area， bacteria were main member in microorganisms and which increased in summer season．Microorganisms of continuous planting fields were more vigorous than those of new fields．The numbers of bacteria increased with increasing years of planting．The actino．Mycetes had same tendency to the bacteria but the numbers were low．The numbers of fungi were low and variation of the numbers with planting years changed according to the area of fields．In the fungal flora，a few cellulose decomposers such as Penicillium and Trichoderma were dominant，and sugar or lignin decomposers were few．Antagonists were recognized in the part of actinomycetes mainly in continuous planting fields．From these results showed that the majority of microfloras in this semi-arid region were bacteria which inhabited in micro-pore spaces．But fungi，which lived in macropore that did not develop in this region even in mature fields，were little．There is a need to pay more attention to the physical amelioration in soil structure in this area so as to provide a favorable ecology environment for developing of microorganisms．