Temperature measurements inside closed vessels can prevent equipment damage and safety accidents caused by high or low temperatures. Most of the existing studies on temperature measurement inside closed vessels are intrusive and single-point measurements. A method for visualizing the temperature field of a closed vessel based on acoustic tomography is proposed, in which a positive problem model is established by approximating the acoustic slow function distribution through a radial basis function, a full variational regularization term constraint is introduced into the model, and the acoustic inverse problem is solved by an alternating direction multiplier algorithm. At the same time, a finite element simulation model is established to analyze the propagation characteristics of the acoustic wave in the closed container. The simulation results show that the maximum relative error between the simulated propagation time and the theoretical value is 1.80%, and the error between the reconstructed temperature field and the modeled temperature field is within 3%. Finally, an acoustic temperature field experimental test system is constructed and experiments are used to further verify the feasibility of acoustic temperature measurement, and the experimental results show that the technique can reconstruct the temperature field of closed containers with liquids. This study is important for measuring the internal temperature and preventing overheating faults to ensure the stable operation of the equipment.