A common issue in 3D printing is the deformation of the fabricated product. In this study, we experimentally manipulated the temperature field to examine its effect on the deformation conditions of 3D-printed items during printing, by measuring three major parameters: printing speed, layer thickness, and workpiece size. The layer thickness was set at 0.15 and 0.2 mm. The workpiece dimensions (height × length) were 70 mm × 100 mm and 70 mm × 150 mm, and the width was manipulated as 0.2, 0.4, 0.6, and 0.8 mm. The two workpiece sizes were tested at the same printing speed and layer thickness. The impact of the three parameters on the deformation of printed polylactic acid (PLA) workpieces was analyzed. The layer thickness affected the PLA workpieces, with thicker layers presenting a higher level of deformation. When the printing speed was increased from 30 to 80 mm/s at 10 mm/s intervals, the deformation of 3D-printed PLA workpieces was affected.