The invention provides a water injection well water injection profile measuring method based on a natural gamma ray baseline. The water injection well water injection profile measuring method comprises the following steps: according to the natural gamma ray baseline of a water injection well, the radioactive intensity of an isotopic tracer is selected; according to the radioactive intensity of the isotopic tracer, a corresponding target isotopic tracer is matched, and is released into the water injection well; a downhole instrument is adopted for rapidly tracing the target isotopic tracer, and an isotope gamma peak curve is acquired; according to the natural gamma ray baseline and the isotope gamma peak curve, a water injection profile of the water injection well is acquired. According to the water injection well water injection profile measuring method provided by the invention, the radioactive intensity of the isotopic tracer is selected according to the natural gamma ray baseline of the water injection well, so as to meet the requirement on the amplitude of a radioactive intensity difference between the natural gamma ray baseline and the isotope gamma peak curve during the measurement of the water injection well having an abnormal amplitude of the natural gamma ray baseline.