Abstract: The time-dependent liquid film thickness in horizontal and slightly inclined tubes was measured by using parallel-wire conductance probes,and various wave patterns were obtained.The features of probability density function,probability distribution, auto-correlation,cross-correlation and power spectrum density function of waves were studied in amplitude domain,time domain and frequency domain respectively. The parameters of wave,such as wave amplitude,wavelength,wave velocity and wave period were obtained. The variation of wave parameters with gas,liquid superficial velocities and tube inclination angle were presented.