A discharge lamp system includes a discharge lamp, a power source, a converter, a lamp state signal detection module and a controller. The power source provides a DC power. The converter converts the DC power into a current required by the discharge lamp. The lamp state signal detection module receives a lamp state signal and outputs a lamp state detection signal. The controller processes the lamp state detection signal and a given synchronization signal to generate an average lamp current signal and a pulse current signal, and then processes the average lamp current signal and the pulse current signal to generate a control signal. The controller performs current control of the discharge lamp through the converter according to the control signal. Furthermore, a method for controlling a discharge lamp is also disclosed herein.