This research received financial support from the National Natural Science Foundation of China(Grant No.42030105,No.42204006,No.42274011,No.42304095),Funded by State Key Laboratory of Geo-Information Engineering and Key Laboratory of Surveying and Mapping Science and Geospatial Information Tech-nology of MNR,CASM(Grant No.2024-01-01),Open Fund of Hubei Luojia Laboratory(Grant No.230100020,230100019),the China Postdoctoral Science Foundation(Certificate Number:2023M743580)and the Key Project of Natural Science Research in Universities of Anhui Province(No.2023AH051634).The authors express their gratitude to various entities that facilitated the study.The International GNSS Service(IGS)is acknowledged for providing BDS observations,precise ephemeris products and igs14.atx file.Additionally,appreciation is extended to the IERS for supplying IERS EOP 20C04,and to the China Satellite Navigation Office for furnishing PCO corrections for BDS-3.Special thanks are extended to Maorong Ge for the PANDA software,which proved invaluable in the course of this research.At the same time,we like to express our gratitude to Maorong Ge for the PANDA software.The availability of multi-frequency BDS-3 and BDS-2 observations provided freely by IGS(https://cddis.nasa.gov/DataandDerivedProducts/GNSS/GNSS_data_and_product_archive.html)and the precise ephemeris files,igs14.atx files are provided freely by IGS and MGEX(https://cddis.nasa.gov/archive/gpsdata).The PCO corrections for BDS-3 files can be found on the website of the China Satellite Navigation Office(https://www.beidou.gov.cn/yw/gfgg/201912/t20191209_19613.html).The Bulletin A and IERS EOP 20C04 time series come from the website of IERS(https://www.iers.org/IERS/EN/Home/home_node.html). （Grant No.42030105,No.42204006,No.42274011,No.42304095）