Principally after any manufacturing process, there will be some residual stress, remained in the products, having its own stress distribution based on the characteristics of manufacturing process. To obtain the desired accuracy and quality of the product, we need to relieve a large amount of residual stress. Among stress relief processes used these days, are heat treatment and vibrational treatment. As far as the basic of stress relief process is concerned, they are similar to each other, since both make the part relieve some stress, by imposing some plastic deformation in the part. The principle of this phenomenon is that, the stresses made by loads generated by heat or vibration, is summed with the residual stresses, and it exceeds the stress yield stress. The main purpose of this project is to investigate the main factors affecting the vibrational stress relief process, including, amplitude or load, loading frequency, and number of cycles. The main plan of this project implies that the part having residual stress, undergoes a vibrational stress relief process, then the mentioned factors are considered, to check how much they can reduce the measure of residual stress in the part. Analysis and investigation of this problem is performed on a cantilever beam. This project is done on three different phases, including theoretical analysis, simulation, and experimental work. In theoretical phase, a bending moment induces the residual stresses in the beam. Then a reverse bending moment applies the first cycle of our alternative loading. In this way we can investigate the effect of different parameters of vibrational loading, and check how efficient each one is. To do this, the results of numerical analysis is obtained and the amount of relieved stress after applying the first cycle of vibrational loading, for a cantilever beam made from the desired material is obtained via derived equations. For simulation part, vibratory stress relieving parameters are investigated again for a cantilever beam. The parameters comprise two factors having four levels, plus a one level factor. In overall, 48 simulated tests were evaluated and the optimized levels of factors are obtained. The results of simulation phase are then compared with the results of an experimental test done on a cantilever beam which is first machined, and then vibrated. The comparison is done using hardness property and elastic modulus obtained via the nano-indentor device. The results, imply an important point about the main parameters, and it's about the analogousness of optimized ranges for parameters in all three phases. In other word, the good area for the parameter frequency is less than resonant frequency while the time period doesn't need not to be in higher levels. These ranges for these parameters plus the medium level of loading usually yield in acceptable results. Key Words: Vibrational stress relief, Residual Stress, Plastic limit