Abstract: This paper presents the results of a series of laboratory experiments on internal solitary wave in a two layer fluid system.The int ernal solitary waves (ISWs) of variable amplitudes and types were experimentally arranged from several physical variables,including the different layer thickness ratios H₁/H₂,the interface differences η₀,and the density ratios ρ₁/ρ₂.The wave flume used in this experiment is 12 meter long with a cross section 0.5 m wide and 0.7m in height.Five ultrasonic probes placed at equidistance record the interface fluctuations.The data collection and processing were carried out through control software,Multi Nodes Data Acquisition System (MNDAS).This paper reports physical properties related to wave propagation.By comparing the relationship between nonlinear parameter and characteristic wave frequency,experimental results agreed well with the KdV and mKdV solutions.