Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f(o) and superficial gas velocity U-sg under fixed flowrate of oil-water mixture Q(mix). The dynamics of oil-in-water type slug flow becomes more complex with the increase of U-sg fixed flowrate of oil-water mixture. The change of f(o) leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.