Abstract: A new research method is employed to study vapor water two phase flow. This method combines the timefrequency localization of wavelet transform and fractal theory. It studies the density wave oscillation of vapor water two phase flow based on the analysis method of nonlinear complex system. This novel method not only studies original objects directly, but also does the timefrequency and nonlinear analysis at the same time. The fractal characters of the oscillation parameters of vapor water two phase flow are detected by wavelet functions from the original experiment data.