Taking into consideration the influence of bubble cluster secondary sound radiation, the dynamic equation of spherical bubble clusters is obtained for two bubble clusters co-existing in the same ultrasonic field. Based on the original dynamic equation, the resonance response characteristics of the two-bubble-cluster oscillation system in ultrasonic field are discussed. Results showed that there are two resonance frequencies in this system, that is, low resonance frequency and high resonance frequency, due to the interaction between oscillating bubbles in the bubble cluster, and the two resonance frequencies are related with the bubble's eigenfrequency. The eigenfrequency of the bubbles is related to the bubble cluster's initial radius, bubble cluster's size and the number of bubbles. The coupling between bubble free vibration and driving acoustic may arouse the bubble's forced vibration, whose amplitude and initial phase are related to the bubble initial radius, bubble number density and driving sonic frequency.