Abstract: The BeiDou Navigation Satellite System (BDS-3) officially began providing global services on 31 July 2020. As the core component of satellite navigation systems, the space segment’s service capability determines the overall system performance. This paper first introduces calculation and analysis methods for broadcast orbit errors, broadcast clock errors, Signal-in-space range error and broadcast ionospheric errors. Then, based on the final products of German Geosciences Research Centre (GFZ) and International Global Navigation Satellite System Monitoring and Assessment System (iGMAS), it conducts an evaluation of the changes in broadcast ephemeris accuracy and ionospheric model precision throughout a complete cycle from 2020 to 2025. Research shows that the BDS-3 broadcast orbit error shows a clear dependence on satellite type, with MEO satellites outperforming IGSO satellites. Compared with GFZ products, the 95% RMS of the radial, along-track and cross-track error falls from 0.104, 0.482, 0.589 m respectively in 2020 to 0.080, 0.351, 0.364 m respectively in 2025; and compared with iGMAS products, these data fall from 0.086, 0.386, 0.461 m respectively in 2020 to 0.073 m, 0.341 m, 0.350 m in 2025. Regarding broadcast clock error, based on GFZ products, the 95% RMS improves from 0.705 m in 2020 to 0.540 m in 2025; and based on iGMAS products, the 95% RMS in 2020 is 0.811 m and 0.640 m in 2025. The SISRE of MEO satellites is generally smaller than that of IGSO satellites, and the statistical accuracies of 95% RMS of SISRE in 2020 based on GFZ and iGMAS products reaches 0.705 m and 0.817 m, and in 2025 reaches 0.549 m and 0.645 m, respectively. In terms of ionospheric model errors, throughout the evaluation period, the Klobuchar model exhibited a relatively broad distribution range of VTEC values. The BDGIM model demonstrated a more concentrated frequency distribution in the low VTEC intervals, while the Klobuchar model showed a relatively dispersed distribution in the high VTEC intervals. Compared with CODE and IGMAS ionospheric products, during the solar minimum period (2020), the BDGIM model achieved average VTEC RMS values of 3.193, 6.240, 1.570 TECU and 3.176, 6.790, 1.480 TECU, respectively, while the Klobuchar model yielded 7.359, 35.440, 4.350 TECU and 7.367, 35.930, 4.140 TECU, respectively. During the solar maximum period (2025), the average VTEC RMS values increased to 11.481 TECU and 10.493 TECU, 22.211 TECU and 21.802 TECU, respectively. Based on CODE products as reference, the maximum and minimum VTEC RMS values for the Klobuchar model and BDGIM model were 34.500, 10.400 TECU and 35.330, 6.640 TECU, respectively. The corresponding data referenced against IGMAS products reached 33.810, 10.000 TECU and 35.950, 5.890 TECU, respectively. And the assessment results can provide support for BDS performance optimization.