The invention relates to a method for determining the network voltage safe threshold value in a wind power plant collected area, and belongs to the technical field of power system safety and control. The method includes the steps of firstly, calculating the permitted voltage range of each wind power plant on the wind power plant side to ensure that draught fans on each wind power plant side are not out of service in the normal running process; secondly, uploading the calculation results of all the wind power plants to a power gird wind power collection station control system, calculating the idle output constraint on the power grid wind power collection station side, and returning the calculation result to all the wind power plants; conducting iteration according to the two steps till convergence is achieved. According to the method, the voltage safety constraint of the wind power plants and the main network side is taken into full consideration, and it can be ensured that after one wind power plant is out of service, the other wind power plants can normally run. The network voltage safe threshold value can be solved through rapid iteration, the calculated network voltage safe threshold value has certain robustness for the active power output of the wind power plants, and voltage control of a power grid is facilitated.