It is very important to monitor the quenching and boiling process of fuel cladding under severe accident conditions in nuclear reactors. This study explores the flow heat transfer and acoustic characteristics during quenching process and boiling visualization experiments along with Acoustic Emission (AE) signal experiments were conducted on FeCrAl rods, with thermocouples used to measure the internal temperature changes of the rods. The surface temperature and heat flux density of the rods were calculated through the Sequential Conjugate Gradient Method (SCGM) inversion method. Hydrophones were used to synchronously monitor the AE signals during the quenching and boiling process, and Fast Fourier Transform (FFT) and spectral analysis were utilized. The study found that the transitions in each stage of the quenching and boiling process are closely related to the AE signals, with the heat flux density being positively correlated with the sound pressure intensity, reaching a maximum at the critical heat flux density (qCHF). This provides a basis and safeguard for guiding practical engineering applications and ensuring the safety of pressurized water reactors.