The invention discloses a single-point reliability redundancy method of a photoelectric encoder for a satellite. The method comprises the following steps that absolute angle data, incremental angle data and medium fine code increment data are calculated, and if the absolute angle data is equal to the incremental angle data, the photoelectric encoder outputs the absolute angle data; if the absoluteangle data is not equal to the incremental angle data because of abnormality in a fine code channel, the photoelectric encoder outputs the medium fine code increment data; and if the absolute angle data is not equal to the incremental angle data because of abnormality in a coarse code channel or a medium fine code channel, the photoelectric encoder outputs the incremental angle data. According tothe single-point reliability redundancy method of the photoelectric encoder for the satellite, a function allowing an absolute mode to be autonomously switched to an incremental mode when any internal phototube and a signal channel of the photoelectric encoder fails is owned by the photoelectric encoder, so that the single-point reliability redundancy of the photoelectric encoder for the satellite is realized, and the product reliability is improved.