Ionospheric correlation plays a key role in ionospheric data assimilation, which describes the statistical relationship between different ionospheric parameters or locations, capturing the dependencies and similarities between different regions of the ionosphere. Ionospheric correlation time is an important representation of ionospheric correlation. The ionospheric correlation time is an important parameter, which contains the temporal variability, structure and dynamics information of the ionosphere. This parameter can be directly used to improve the ionospheric data assimilation model. Therefore, this paper proposes an optimization scheme for the ionospheric assimilation system based on ionospheric correlation time. For the same ionospheric assimilation system, different values of correlation time will have a significant impact on the assimilation results. This paper compares the assimilation results when the ionospheric correlation time is 1.5 hours and 2.5 hours. The results show that in mid-to-high latitudes It is more reasonable to use a larger ionospheric correlation time; while it is more reasonable to sample a smaller ionospheric correlation time in mid-and low-latitude areas. Therefore, this paper recommends classifying and calculating the correlation times in different regions to make the ionospheric assimilation results closer to the real values. In-depth research on ionospheric correlation time will help improve the accuracy of ionospheric assimilation systems and help researchers gain a more comprehensive understanding of ionospheric correlation.