Real-time monitoring of blade vibration parameters is the key to ensure the healthy operation of aero-engines. The traditional blade tip timing sensor signal preprocessing method could produce a large timing error due to the wide range of rotor speed (20~ 20 000 r/ min), which affects the identification accuracy of blade vibration parameters. By analyzing the sample rate conversion model, a blade tip timing signal preprocessing method based on spatial transformation is proposed, which converts the equal-time sampling of the blade tip signal into equal-angle spatial sampling to achieve high-precision blade tip timing signal acquisition. The third-order Lagrange interpolation Farrow structure and through pipeline optimization techniques realize the balanced design of logic resource occupation and data processing rates on the field programmable gate array. Experiments show that this method can effectively complete the equal spatial angle sampling and reduce the influence of rotation speed change. When the real-time speed is 1 000 ~ 8 000 rpm and the reference speed is 3 000 rpm, the vibration displacement measurement error of this method is within 20. 19 μm, which is much lower than that of traditional displacement measurement methods. The measurement accuracy of arrival time and blade vibration displacement is improved.