The invention provides a method for realizing automatic calibration of a PLC analog input / output module channel. According to the technical scheme, a process instrument, a
switch matrix, an analog input / output module, M channels and an upper computer are included. And the upper computer issues configuration to the process instrument, reads data, issues configuration to the
switch matrix, and receives calibration results of each channel of the analog quantity input / output module. The upper computer evaluates the calibration progress of each channel according to the
calibration result of the analog quantity input / output module and the read data of the process instrument, and outputs corresponding issuing configuration according to the progress, so that the process instrument adjusts the analog quantity
signal output / measured by the process instrument, and the
switch matrix adjusts the communication path of the process instrument; and further enabling the analog input / output module to continue to execute the calibration program until all channels of the module are calibrated. According to the invention, wiring errors, key errors and reading errors possibly caused by manual operation can be avoided; the influence of different
contact effects caused by manual plugging each time on the channel calibration effect can be reduced; the deviation of channel calibration caused by reading when the
system state is not stable can be reduced; the multi-channel calibration efficiency of the analog input / output module can be improved.