Competition between stimulated dynamic light scattering (SDLS) and stimulated Raman scattering (SRS) in CS2 liquid-core waveguide is studied by timeresolved pump pulse duration and pump density dependent experiments. It is found that the threshold of SDLS is dependent on the pump pulse duration. The competition between SDLS and SRS implies that SDLS consists of two contributions, one relates to the increasing rate of transient pump power density at the rise-time of pump pulse;the other relates to the transient pump power density, and dominates around the peak of high density pump pulse. Their mechanism is discussed.