Abstract: The natural frequencies of 66 double cylindrical velocity transformers were measured, and the law of variation of the natural frequency of the double cylindrical velocity transformer vs. N, the ratio of the diameters of two ends, and a, the ratio of diameter to length, was found experimentally. The natural frequencies of 126 double cylindrical velocity transformers with circular arc transition were measured. The law of variation of the natural frequency of this type of velocity transformer vs. parameters N and R/d was found experimentally also. The results were presented in the form of a family of curves for designing velocity transformers, affording the design of double cylindrical velocity transformers with natural frequencies accurate to within 1%.