In this article, the influence of modified couple stretch theory (MCS) on the vibration behavior of initially stressed small scale beam is investigated. The model is constructed depending on the Euler–Bernoulli beam theory. In this work, the generalized heat equation with thermal relaxation time is applied to the model under investigation. The analytical distributions of temperature, deflection, displacement, flexure moment, and stress due to MCS is obtained employing Laplace transform technique. The temperature pulse and couple stress effects on the field variables of the microbeam are illustrated. Comparisons among the influences of the initial stress are also discussed.