There are kickpoints on the curves about critical heat flux (CHF) and start point of minimum film boiling (Tmin) of vapor liquid two phases flow. Changes of gradient occur round these kickpoints. There must be of singularity at the kickpoints in mathematics. Detection of signals can be obtained through wavelet translation

using the excellent local characteristics for space and frequency filed. The singularity and changes

which are hidden in signals

can be discovered by the characteristics of wavelet. Wavelets of boundary detection are used in vapor-liquid two phases flow for detecting CHF and Tmin. This wavelet analysis method can detect

orient and rate these points of two phases flow and is confirmed by the experiments results. This study initiates a new experimental method for vapor-liquid two phases flow.