The invention provides a method for detecting the sealing performance of a cavity, and a mobile terminal. The method is applied to the mobile terminal. The mobile terminal comprises the cavity, an electroacoustic unit arranged in the cavity and an audio output member electrically connected with the electroacoustic unit. The method comprises the steps of: inputting a control signal to the audio output member, and enabling the audio output member to output frequency sweep signals with different frequency values according to a preset time interval; obtaining the input voltages of the electroacoustic unit when the frequency sweep signals act on the electroacoustic unit; according to the input voltages, determining a resonance frequency point of the cavity; and determining the sealing performance of the cavity according to the resonance frequency point. According to the invention, the detection is carried out by the mobile terminal itself, no specific testing device and testing environment are needed, dismounting is not needed, and the problems in the prior art that the detection process is tedious and requirements of large-batch rapid detection cannot be met are solved.