The invention relates to a heat dissipating system for prolonging the service life of a stage electric discharge lamp. The heat dissipating system comprises a heat dissipating module and a control module. The control module comprises a time reference unit; the heat dissipating module dissipates heat of the electric discharge lamp; the control module controls the heat dissipating module to open; the time reference unit times and enables the control module to open the heat dissipating module in a delayed manner, and the time reference unit starts to timing when the electric discharge lamp is switched on. A heat dissipating method comprises the following steps: when the electric discharge lamp is switched on, the time reference unit starts to time t1 second; and after timing, the heat dissipating module is opened to dissipate heat of the electric discharge lamp. When the electric discharge lamp light source is switched on, an ideal working temperature is achieved quickly and influence onthe service life of the light source is greater than that of cold and hot stress. The light source is heated more quickly by adopting a method of stopping a heat dissipating fan, so that the service life of the electric discharge lamp light source is prolonged. The time t1 is a delayed time set by those skilled in the technical field according to experience, for example, 10 seconds, and the electric discharge lamp light source is substantially at the ideal working temperature.