Silicon photomultiplier (SiPM) has recently been used in several space-borne missions for scintillator readout, thanks to its solid state, compact size, low operating voltage and insensitivity to magnetic fields. However, a known issue of operating SiPM in space environment is the radiation damage and thus the performance degradation. In-orbit quantitative study of these effects is still very limited. In this work we present in-orbit SiPM characterization results obtained by the second detector of Gamma-Ray Integrated Detectors (GRID-02), which was launched on Nov. 6, 2020. An increase in dark current of ∼100 µA/year per SiPM chip (model MicroFJ-60035-TSV) at 28.5 V and 5 • C is observed, and consequently the overall noise level (sigma) of GRID-02 detector increases ∼7.5 keV/year. The estimate of this increase is ∼50 µA/year per SiPM chip at -20 • C, which indicates good effect of using a cooling system.