Abstract: In order to study the influence of the airstream velocity and droplet initial diameter on the secondary atomization process and the Rayleigh-Taylor wave, the experiment of recording the breakup process of a kerosene droplet at high Weber numbers was conducted, where the photographs were taken by a high speed camera.The analysis based on the Rayleigh-Taylor instability theory which includes viscosity and surface tension was done. The calculation was conducted in order to predict the wavelength of the most unstable Rayleigh-Taylor wave and breakup time, and the results were compared with the experimental data. The results indicate that the catastrophic breakup takes place when the Weber number is greater than 321. The airstream velocity and droplet initial diameter have great influence on the wavelength of the Rayleigh-Taylor wave with the maximum growth rate, the growth rate and the critical wavelength. The Rayleigh-Taylor instability theory which contains the viscosity and surface tension fits the experimental data well when being used to predict the wavelength of the most unstable Rayleigh-Taylor wave, the error less than 6%. Setting the value of M to be 8.9 can minimize the breakup time error.