Abstract: Acoustic cavitation is widely used in many fields, such as surface cleaning, biological imaging, and material synthesis. Interface stability of gas bubble plays an important role for the effects of cavitation. In this paper, considering the influence of liquid viscosity and surface tension, the perturbation method is used to obtain the analytical solution of the governing equation for the radial oscillation of the bubble. A model of interface stability of gas bubble in the acoustic field with single/dual-frequency excitations is established and solved, and the critical radius of the bubble oscillation is obtained. When the radius of the bubble in the initial equilibrium is less than the critical radius, the interface of the gas bubble remains stable. Otherwise, the interface of the gas bubble becomes unstable. In a single-frequency-excited acoustic field, under low frequency excitation, the low-order critical radii of the bubble are near its resonance radius; the high-order critical radius of the bubble, not influenced by frequency change, is equivalent to the same high-order critical radius of the bubble under high-frequency excitation. The critical frequency values of high and low frequencies under different excitation amplitudes are obtained. In an acoustic field under dual frequency excitation, the influences of key parameters (i.e. the ratio of the frequencies, different ratios of pressure amplitudes and total acoustic pressure amplitude) on the critical radius of bubble interface instability are discussed in three cases (i.e. double low frequencies excitation, high frequency + low frequency excitation and double high frequencies excitation).