Luminescence technique has been shown to have great potential in low-temperature (< 100 °C) themochronology. This study investigates the kinetic process of luminescence in a cooling system. We present a new formula that can be used for determining the cooling age based on luminescence-thermochronology. The cooling rate can be obtained directly from a plot of luminescence age versus the present temperature. We show that the application and capacity of luminescence-thermochronology are significantly controlled by the saturation of luminescence and environmental dose rate.