The solar flare represents the primary source of eruptions that give rise to space weather. Its rapid expulsion of material in the form of a jet is believed to be the potential catalyst behind the termination shock (TS) that occurs at the apex of the magnetic flux loop. Within this unique cosmic setting, it becomes particularly intriguing to delve into the fundamental mechanisms responsible for the initial acceleration of particles and to scrutinize their role in the generation of solar energetic particles (SEPs), extending all the way to the phenomenon known as ground level enhancement (GLE). In our current research, we are focusing on uncovering the relationship between GLE events and the termination shock associated with solar flares. To achieve this, we employ a dynamic Monte Carlo simulation technique to model the behavior of the flare termination shock. In this theoretical framework, thermal particles that are part of the high-speed outflow from magnetic reconnection events penetrate the shock front located at the summit of the photospheric loop. Through numerous cycles of interaction with the shock front, these particles undergo successive energy gains. Consequently, our simulation reveals intricate details of the energy spectral structure and the emergence of a pronounced high-energy "tail" among the accelerated protons. Based on these findings, we hypothesize that the termination shock acceleration mechanism serves as a primary source of energetic particles,  although it does not lead to GLEs directly, it effectively seeding the subsequent interplanetary acceleration processes that culminate in the production of GLEs.