A regional reanalysis product—China Ocean Reanalysis(CORA)—has been developed for the China’s seas and the adjacent areas. In this study, the intraseasonal variabilities(ISVs) in CORA are assessed by comparing with observations and two other reanalysis products(ECCO2 and SODA). CORA shows a better performance in capturing the intraseasonal sea surface temperatures(SSTs) and the intraseasonal sea surface heights(SSHs) than ECCO2 and SODA do, probably due to its high resolution, stronger response to the intraseasonal forcing in the atmosphere(especially the Madden-Julian Oscillation), and more available regional data for assimilation. But at the subsurface, the ISVs in CORA are likely to be weaker than reality, which is probably attributed to rare observational data for assimilation and weak diapycnal eddy diffusivity in the CORA model. According to the comparison results, CORA is a good choice for the study related to variabilities at the surface, but cares have to be taken for the study focusing on the subsurface processes. A regional reanalysis product-China Ocean Reanalysis (CORA) -has been developed for the China’s seas and the adjacent areas. In this study, the intraseasonal variabilities (ISVs) in CORA are assessed by comparing with observations and two other reanalysis products (ECCO2 and SODA). CORA shows a better performance in capturing the intraseasonal sea surface temperatures (SSTs) and the intraseasonal sea surface heights (SSHs) than ECCO2 and SODA do, probably due to its high resolution, probably due to its intraseasonal forcing in the atmosphere ( especially the Madden-Julian Oscillation), and more available regional data for assimilation. But at the subsurface, the ISVs in CORA are likely to be weaker than reality, which is probably attributed to rare observational data for assimilation and weak diapynal eddy diffusivity in the CORA model. According to the comparison results, CORA is a good choice for the study related to variabilities at the surface, but cares have to be taken for the the study focusing on the subsurface processes.