The invention discloses a decoding circuit of a spaceborne absolute type photoelectric axial angle encoder based on DSP (Digital Signal processor) and relates to a decoding circuit; the invention solves the problem that the change of the photoelectric current output by the photoelectric axial angle encoder results in the code skipping of the decoding result because of the changes of the aerospace environment temperature. The decoding circuit is composed of a sampling module, a microprocessor module and a mode selection module; the sampling module acquires a coarse code signal, an intermediate precise code signal and a precise code signal of the outer encoder; in the parameter acquisition mode, the microprocessor module acquires the decoding algorithm parameter by the computation; in the decoding mode, the microprocessor decodes the coarse code data according to the encoding manner; the values of ESIN, ECOS, GSIN and GCOS are acquired by using the acquired decoding algorithm parameter; intermediate precise code data and precise code data are subdivided in the table look-up method and then the final position data information is acquired after two corrections. The invention is suitable for the occasions using high-precision position sensors in the aerospace field.