Thermoacoustic engine is an energy conversion device that uses the energy carrying capacity of sound waves to generate sound power from thermal energy. Although it is not difficult to build thermoacoustic engines due to having no moving parts, many researchers have always tried to reduce the temperature difference required to run thermoacoustic engines, so that these devices can be used in most industries. To investigate the onset conditions of the system, temperature changes in the stack section of a standing wave Thermoacoustic engine were investigated. Numerical analysis of temperature changes along the stack, was performed using the rotts thermoacoustic equations. The temperature was calculated instantaneously along the stack, and this process continued until the thermal equilibrium was established in the system. A standing wave with an open end was designed and built to validate the temperature curves obtained at different moments. This thermoacoustic engine was able to display the temperature instantaneously along the stack with parallel plates structure. The data obtained from the experimental tests and the temperature changes diagram resulting from the numerical solution method, showed a good agreement with each other for the onset process in the system.