Abstract: Although some types of electrical vibrograph have been applied in the rccent years,the Geiger mechanical vibrograph is still used for, measuring and recording torsional vibration of engine shafting system because it is suitable especially for torsional vibration measurement in lower frequency range. It is known that the trace drawn by recording pen on paper strip of Geiger torsiograph appears so small for analysis,that the results of testing must be magnified photographically,in general,and then decomposed into some harmonic components by hand or other instrument.This procedure is very difficult and lab orious. In order to transform the movement of recording pen into electrical signal outputf which can be treated conveniently,a thin mild plate adheres to the end of transmisson rod of Geiger torsiograph,and an electrovortex transducer is set near the plate The electrical signal can be delivered through wires into the vibration measuring equipment,oscilloscope,and microcomputer by which the signal of torsional vibration of engine shafting system is sampled and decomposed into some harmonic components by means of FFT algorithm. In this paper,it is introduced that the results are o brained from torsional vibration test of a diesel propulsion plant using Geiger torsiograph which can produce electrical signal and draw graph on the pa per strip simultaniously.