A method, an apparatus, and a device for identifying a cell string fault in an optoelectronic system, where the method includes obtaining at least two groups of current-voltage (I-V) values of a first cell string in the optoelectronic system, performing fitting processing according to the at least two groups of I-V values using a predetermined physical string model to obtain at least one characteristic parameter of the first cell string, and comparing the at least one characteristic parameter with a pre-obtained standard characteristic parameter to determine whether the first cell string is faulty, or performing curve fitting processing on collected data using the physical string model. Therefore, identifying the cell string fault in the optoelectronic system is not affected by inconsistency of environments, and processing efficiency and accuracy of string fault identification are effectively improved.