The invention relates to a method for reactive substitution between a wind power plant dynamic reactive compensation device and draught fans and belongs to the technical field of reactive automatic regulation of voltage of a wind power plant. The method comprises the steps that the modified value of reactive upward regulating quantity and the modified value of reactive downward regulating quantity are determined according to the current total reactive value, the current reactive upward regulating quantity and the current reactive downward regulating quantity, which can be obtained by a draught fan monitoring system, of all wind power, the reactive substitution quantity is determined according to the reactive regulating step size of the dynamic reactive compensation device, the reactive substitution quantity is verified according to the reactive upward regulating quantity and the reactive downward regulating quantity of the wind power, and finally the reactive set value of the dynamic reactive compensation device and the reactive set value of each draught fan are determined respectively. According to the method for reactive substitution between the wind power plant dynamic reactive compensation device and the draught fans, smooth transition is kept in the whole process of substitution between the voltage of a grid-connecting point of the wind power plant and the voltage across the end where the draught fans are located, and safety and reliability of operation of the wind power plant are improved.