This study presents a numerical analysis of a prestressing setup developed for testing small pretensioned concrete slab specimens. The main objective is to evaluate the performance of the steel plates under the tensile forces generated during prestressing. A finite element model was developed in Robot Structural Analysis to examine the stress distribution and verify whether the selected plate thickness was adequate under a prestressing force of 70 kN per tendon. Plate deformation was also considered because excessive movement could affect the stability and accuracy of the setup. IPE steel sections were therefore added to control plate deformation and prevent the supporting beams from moving toward each other during stressing. The maximum normal stress was 196.11 MPa, which was below the adopted allowable stress of 213 MPa. The configuration without upper IPE120 sections showed excessive deformation, whereas the modified configuration reduced the maximum displacement to 2 mm. This study provides a numerically verified anchorage configuration with adequate strength and deformation control for testing small pretensioned concrete slab specimens under a tendon force of 70 kN.