Slug flow is one the most complicated flow regime in industrial process that is seen for wide range of fluid flow. However, there are always some differences between experimental and numerical results obtained for slug flow. Proceeding the perivious attempt on the selection of the best turbulent model for numerical simulation, the slug flow is simulated numerically in two dimension by applying implicit VOF method and k-ε RNG turbulent model. To extract the slug flow parameters accurately FLUENT solver is used. The differences of the obtained results with and without turbulent model during slugging is also presented. To overcome this complicated flow behavior, a new user defined function code is developed. This UDF computes and predict slug parameters from FLUENT solver result without increasing the computational cost. The important slug parametrs are presented which are: liquid slug body velocity, liquid film velocity, slug front and tail velocity, slug center position and length, slug front and tail positions, pressure difference across slug, wall shear stress, slug mixture velocity, slug initiation time and position from the duct inlet. These parameters are analyzed and discused in details after that they had been validated