Abstract: 90Sr is one of the main nuclides in environmental radioactive pollution monitoring, the 90Sr specific activity in soil is an important data for environmental monitoring, and especially it needs be accurately measured when the specific activity is above 1 Bq/g. Usually, the 90Sr in soil is determined by radiochemical methods. 90Sr or daughternucleus 90Y in the soil is separated by radiochemical methods and then the β ray is measured to calculate 90Sr in the soil. Because of the complex chemical process, it is difficult to quickly analyze the 90Sr of a large number of soil samples during the decommissioning of nuclear facilities. Measuring the 90Sr90Y βray emitted from the soil surface or the secondary rays produced by the interaction with the soil medium, can realize the direct measurement of 90Sr in the soil. In order to solve the problem of rapid and direct determination of 90Sr in contaminated soil, a laminated plastic scintillation fiber array detector was developed. Through the design of the scintillation optical fiber space layout and the logic setting of multi-channel signal analysis, the β-ray signal from 90Sr-90Y decay can be distinguished. The effective detection area of the detector is 100 mm×200 mm, and the radiation signal is obtained by NIM standard electronic plugin. The detection sensitive part consists of the first, second and third layers of 1 mm square plastic scintillation fiber array, 10 mm PMMA absorber and the fourth layer of 1 mm square plastic scintillation fiber array (the first layer facing the tested soil). At the same time, when the first three layers of scintillation fiber produce fluorescence and the fourth layer does not produce fluorescence, it is recorded as a 90Y decay event. γrays pass through the detector, and the probability of fluorescence in the threelayer scintillation fiber is very low, that is, the detector is not sensitive to γrays and can measure the 90Sr in the soil in a strong γradiation environment. The detector background count rate is 1.98 s-1, the 90Sr detection efficiency is 1.4%, the output count rate and the 90Sr specific activity of the reference soil have a linear fit of 0.999, and the minimum detectable activity is 0.18 Bq/g (5 min). Through the measurement of real contaminated soil and the verification of the measurement results, it is shown that the detector has high accuracy in measuring the 90Sr of soil, which can be used for rapid and direct measurement of the 90Sr of largescale soil samples during the decommissioning of nuclear facilities and environmental census.