The invention relates to a method for realizing active power emergency control of a photovoltaic power station employing collecting line switches, and belongs to the technical field of active automatic adjustment of the photovoltaic power station. The method comprises the following steps: obtaining an active power emergency instruction of the photovoltaic power station from an automatic gain control (AGC) system of a power grid dispatching terminal; with the instruction as an upper limit Pmax of active power emergency control of the photovoltaic power station, collecting active power of a grid-generation point delivery line of the photovoltaic power station and various collecting lines and the states of various collecting line switches; if the online total active power Pgate is greater than the upper limit Pmax, judging that the total active power exceeds the standard; and after the exceeding time exceeds the emergency control exceeding allowable delay, with the difference value between the Pgate and the Pmax as the regulating variable Pset, carrying out fast removal by selecting the active combination of the collecting lines which are slightly greater than the regulating variable, so that the removed active power is as little as possible on the basis of meeting the dispatching instruction. According to the method, the active power emergency control of the photovoltaic power station is realized by the collecting line switches; the condition that the online total active power of the photovoltaic power station rapidly reaches the dispatching instruction is ensured; and electricity is generated as much as possible.