A new high-accuracy spectral calibration is applied to monitor and correct spectral shift of solar backscattered ultraviolet spectroradiometer (SBUS) in launch and flight. A high-resolution reference spectrum is used to convolve with instrument′s slit function. The convolved results is matched with corrected spectrum measured by SBUS, and evaluation function is founded to calculate the value of the spectral shift that minimizes the difference between reference and measured spectrum. For SBUS, the optimal spectral shift is 0.10 nm. Finally, the result is validated by standard spectrum of on-board mercury lamp and the maximal error is 0.01 nm, which meets instrument′s requirements. The experimental results verity feasibility and precision of the high-accuracy spectral calibration.