With the help of the PLK coordinate perturbation technique the equation of motion of a spherical bubble in a viscous compressible liquid is derived by taking account of the gas density inside the bubble, and the effects of the liquid compressibility on the variations of the bubble radius, bubble wall velocity and bubble wall pressure with time and the maximum impulse pressure accompanying the bubble collapse are investigated. Further, by considering the liquid compressibility. the pressure distributions in the liquid during the collapse and rebound of bubble are numerically obtained, and natural frequency of bubble is analytically obtained. As a result, the relation between the maximum impulse pressure and the bubble natural frequency is numerically clarified.