Shock wave focusing can produce higher pressure and induce cavitation behaviour in the focal region. Experimental study was carried out based on an underwater shock wave focusing system and an optical arrangement for taking high-speed photographs. The physical process of the cavitation behaviour and the relation between bubble dynamics and pressure were analyzed by comparing between the pressure-time histories and the high-speed photographs. The bubble dynamics was modeled with modified Rayleigh-Plesset equation; the results indicate that the characteristic of bubble dynamics and the duration of bubble behaviour are sensitive to pressure field, and experimental results and theoretical results agree well.