Temperature has a certain impact on the magnetic properties of soft magnetic materials, and temperature rise parameters are crucial considerations in high-frequency transformer design optimization. However, in magnetic characteristics test of soft magnetic materials at different temperatures, the temperature variation time relies on subjective judgment of experimenters. If the heating time is insufficient, the testing accuracy is relatively low, while excessive heating results in low efficiency. Therefore, a self-heating magnetic property measurement method for magnetic rings was proposed, aiming to ensure the measurement accuracy while improving efficiency. Nanocrystalline materials, preferred materials for high-frequency transformers, are used as the study object in this paper, aiming to investigate factors influencing temperature rises of nanocrystalline magnetic rings, and an excitation circuit is subsequently designed to rapidly heat the magnetic rings. Once the magnetic rings reach the target temperatures, they are demagnetized through low-frequency AC attenuating excitations to meet the testing conditions at designated temperatures. The magnetic property parameters are then obtained by using the excitation and measurement circuit. Finally, a traditional constant temperature box of nanocrystalline magnetic rings and a self-heating magnetocaloric characteristic testing system are designed and built. The comparison between measurement results from the two methods validates the improved efficiency of the proposed method on the premise of ensuring the accuracy. By simulating actual temperature rises of magnetic materials, the proposed measurement method reduces the heating time by over 90%, and changes the temperature of the magnetic rings by a constant value, thus achieving advantages of precise, controlled, and rapid temperature changes. This method provides an experimental and data foundation for multi-physics coupling and design optimization in high-frequency transformers.