Abstract: In waterfiood oilfields, zonal waternooding is oftenperformed due to reservoir heterogeneity. Whether or notthe zonal injecting pipe strings in injectors work normally,directly innuences the allotment of injection watcr and theoverall production efficiency. This paper presents a simplemethod to identify the operating conditions of downholepipe strings using zonal testS data, which provides a basisfor rational development of oilfields.