Abstract: This research investigates the utilization of 3D printing technology and the phase transfer method to fabricate photosensitive resin containing the radionuclide ¹³¹I, aiming to simulate the neck-thyroid source model for the efficiency calibration of detectors. Through optimizing the type, dosage, mixing time of the phase transfer agent, as well as the addition amount of ¹³¹I, a well-uniform ¹³¹I photosensitive resin was successfully prepared. By means of 3D printing technology, the thyroid source model was fabricated and a comparative measurement was conducted with the IAEA (International Atomic Energy Agency)/ANSI (American National Standards Institute) neck phantom. The experimental results indicate that the detection efficiency of the thyroid source model prepared using ¹³¹I photosensitive resin is in line with that of the IAEA/ANSI neck phantom, proving the feasibility of 3D printing technology and phase transfer method for preparing photosensitive resin thyroid body source and offering a novel approach for the preparation of other complex heterogeneous source models.