Abstract: Flow pattern quantization formulation is a key to gas-liquid two-phase flow pattern identification. A general gas-liquid two-phase flow experimental facility is established to obtain flow pattern signals in the transition between stratified wavy flow and slug flow. Fractal dimensions of these flow pattern signals are calculated with fractal theory based on wavelet transform. It is proven that the difference between fractal dimensions of the two flow pattern signals is enough to be considered as a new quantization symbol for flow pattern identification.