Langmuir turbulence plays a significant role in affecting the turbulent mixing in the ocean surface boundary layer. Yet our understanding on its temporal evolution in a diurnal cycle is far from sufficient, especially its response to transient forcing and its interaction with the changing stratification. This largely contributes to the biases in parameterizing the ocean surface boundary layer turbulent mixing in ocean general circulation models and climate models. Here we present preliminary results of a set of large eddy simulation (LES) experiments of Langmuir turbulence with various diurnally changing wind, waves and surface buoyancy fluxes. The focus is on the transient response of Langmuir turbulence to the changing ocean surface forcing and background conditions during a diurnal cycle. This represents a largely unexplored parameter space left by previous LES studies of Langmuir turbulence. The effects of such transient response on the turbulent mixing of momentum and tracers in the upper ocean, as well as implications for improving existing Langmuir turbulence parameterizations, will also be discussed.