Out-of-band response (out-of-band light leakage) is a significant factor affecting the radiometric calibration uncertainty of multispectral remote sensor (MsRS). For the MsRs out-of-band response measurement, correction and precision verification, the 443 nm band in multispectral imager using the functions of a novel spectrum-tunable integrating spheres reference light source (STIS) (i.e. discrete waveband and continuous spectrum output functions) was taken for example in batch experiments. After carrying out the out-of-band response measurement, correction and precision verification of multispectral imager, the weighted radiant luminance was amended based on the out-of-band response correction model, and compared with the measuring reference of spectral radiance meter. The results show that the difference between in-band weighted radiant luminance and measuring reference before and after the out-of-band response correction decreases from 8.8% to 2.9%, which confirms the application feasibility of STIS on the MsRS out-of-band response correction.