The invention relates to a correction method and a correction system for merging unit analog channels. The correction method comprises the following steps: at first, storing a first configuration file and a second configuration file respectively corresponding to an AC plug-in and an ADC plug-in; during correction, multiplying a correction coefficient of each channel in the first configuration file by the correction coefficient of the corresponding channel in the second configuration file to acquire a total correction coefficient of each channel; adding a correction phase of each channel in the first configuration file with the correction phase of the corresponding channel in the second configuration file to acquire a total correction phase of each channel; and correcting the corresponding channel according to the total correction coefficient and the total correction phase. When one of the AC plug-in and the ADC plug-in is subjected to an operation fault or needs to be changed, only the faulty plug-in needs to be singly changed, the corresponding configuration file of the faulty plug-in is reloaded into the correction device, the other normally operating plug-in does not need to be changed, and the corresponding configuration file does not need to be changed neither.