Abstract: An engine casing modal experiment and modal parameters extraction have been introduced in the paper.In the power spectrum analysis,the effect of noise was considered.Power spectrum expression mixed with noise was proposed,and it was used to calculate the power spectrum function and finally modal parameters were extracted.The pre-experiment was introduced to determine the approximate scope of the modal frequency,so that we could determine the locations of transducers and excitation point of the vibro-machine.Considering the practical working condition,the white-noise stochastic excitation has been used to simulate the stochastic excitation during the modal experiment.Compared with the computational model,the means of extracting parameter with modal experiment can avoid complicated finite element modeling and simulation.Correlation function was used to checkout the reliability of the experimental data.Modal experiment shows that the parameters of the engine casing are of great importance in improving the structural design of the engine casing,vibration fault analysis,and fatigue life analysis and so on.