The main objective of the study is to model the behavior of residual stresses in shot peened 300M landing gear steel affected by heat treatment. It is well known that residual stresses can have a significant influence on the mechanical behavior of major components under stresses. Therefore, information regarding the stability of existing residual stress states is of significant importance. In this experiment, special attention is paid to consequences of the heat treatment processes on compressive residual stresses induced in material by shot peening. The relaxation in residual stress due to addition of thermal energy by heat treatment at different temperatures and times is investigated. An existing model was used to create a stress relaxation equation for 300M high strength steels. Effect of heat treatment on residual stress distribution at subsurface level is also be examined. The current study will focus on the initial compressive residual stress field produced by common aerospace peening conditions and by how much isothermal exposures alter this stress and factors affecting the stress relaxation as well as fatigue life of the affected components.