Lutetium-yttrium oxyorthosilicate (LYSO) crystal scintillators were originally developed for medical applications. Owing to their high density, small Moliere radius, fast response, and high radiation hardness, LYSO crystals have also suitable for future homogeneous electromagnetic calorimeters. Due to these features, LYSO is considered to be used for the electromagnetic calorimeter part of the Turkish Accelerator Center Particle Factory (TAC-PF) detector. In this research, by employing the GEANT4 toolkit program, we simulated a set of crystal, and their energy resolutions were obtained for different lengths at the energy range of 50 MeV - 2 GeV. Depending on the crystal length, contributions to the constant term of the energy resolution were investigated.