Abstract:Instrument for soil test - annular sword is widely used in the field of highway engineering and construction engineering test, mainly used for preparing soil samples and measuring density. The manufacturing accuracy of geometric dimension and shape and position error is directly related to the accuracy of sampling area and volume, and then affects the density measurement of soil sample. In recent years, the calibration of the annular sword has been paid more attention than ever before. However, up to now, there is no national, local or industrial calibration standard for the annular sword, so the calibration method is not uniform, and the traceability of the measurement value is difficult to be guaranteed. According to the industry standard , the geometric parameters, technical indexes, calibration items, calibration methods and evaluation methods of uncertainty of calibration results are given in this paper. From the perspective of metrology, try to be comprehensive and rigorous, so as to provide reference for relevant calibration laboratories and annular sword users, and put forward valuable suggestions.