A theoretical model of analysis of bubble far-field interference is given, when parallel laser beam is irradiating the bubble in a transparent medium, the interference between refraction beam and total reflection beam comes into being and the thick-inside-and-thin-outside interference rings have taken shape in far field, a formula on optical path length difference and a formula on distance of two parallel exit rays are derived, reasons for thick-inside-and-thin-outside interference rings are analyzed, the method of calculating interference regions and the largest constructive interference ordinal number are given. The diameter of bubble can be measured by method of interference, the size of bubble can be measured in the depths of medium. The diameters of bubbles in the glass water box, plate glass and glass prism have been measured by method of far-field interference, and the measured result of diameter in glass prism by the interference is compared with that by the Abbe comparator, the relative difference of which is 0.9%. The application of measurement in the size of moving bubble, refractive index of gas in bubble, size of optically denser medium ball in a transparent optically thinner medium is expected by method of far-field interference.