In order to promote the application of MERSI II data in the ocean, this paper uses the visible infrared optical imaging remote sensing instrument (VIIRS), which is one of the mainstream sensors for water color remote sensing, as a reference, from the signal-to-noise ratio (SNR) and other aspects to conducte a preliminary assessment of the MERSI II data quality. The results show that the SNR values of MERSI II are higher than 300 in the visible band, and the maximum can reach 900, which meet the water bodies monitoring requirements. The SNR values of MERSI II are slightly lower than that of VIIRS in the visible band and the near-infrared band, and are not much different from VIIRS in the short-wave infrared band. In addition, the radiance calibrated MERSI II reflectance data at the top-of-atmosphere is in good agreement with the VIIRS data, the determination coefficients (R²) are higher than 0.5, and the blue band R² can reach more than 0.9. The mean absolute percentage error (E_MAPE) is less than 30%. The R² in the 670-865 nm band of the Western Pacific is about 0.5, and the E_MAPE is 5%-15%. The R² can reach 0.8 in the 670-865 nm band of China’s coastal waters, and the E_MAPE is 7%-24%. After a simple linear fitting, the MERSI II reflectance data at the top-of-atmosphere is closer to the VIIRS data. The E_MAPE in the visible band drops to 8%, and the blue band drops to 3%. The above results show that the quality of MERSI II data is comparable to VIIRS and can be used for ocean remote sensing applications.