<p>The influence of different tensile stress states (elastic stress, plastic stress) on bainite transformation of 15CrMo steel was studied. It was found that elastic stresses exerted an additional driving force for transformation, thereby enhancing its kinetics and increasing the volume of bainite. Concurrently, the bainite laths become slender due to the elastic stresses. The promoting impact of plastic stress on bainite transformation is influenced by a combination of mechanical driving force and plastic strain. On one hand, plastic stress provides additional driving force for transformation, accelerating its kinetics and increasing the volume of bainite. On the other hand, dislocations introduced by plastic strain enhance the stability of austenite, leading to a decrease in the volume of bainite. The combined impact ultimately leads to a trend where the volume of bainite first increases and then decreases with increasing of plastic stress. However, the initial transformation rate under plastic stress continues to rise, primarily due to plastic strain providing some nucleation sites for transformation. Under both elastic and plastic stresses, the bainite bundles exhibit selective orientation and variant selection phenomena, with a more pronounced effect observed under plastic stresses due to the different driving forces provided by elastic/plastic stresses on different variants.</p>