An empirical mode decomposition (EMD) model for BeiDou Navigation Satellite System (BDS) code bias has been established upon the observation model of multiple global navigation satellite systems (multi-GNSS). To validate the correctness and effectiveness of the model, seven days from day of year (DOY) 213-219, 2015 from eight Multi-GNSS Experiment (MGEX) stations were processed. Results show that after code bias correction, the standard deviation of the multipath combination (MP) series on B1 and B2 frequencies decreased by 38.63 % and 17.4 %, respectively. The timespan needed for convergence in BDS precise point positioning (PPP) was improved by 7.9 % after inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) code bias correction, and another improvement of 11.4 % was generated by applying geostationary orbit (GEO) code bias correction. Despite the improvement of convergence time, the accuracy of the single-day solution barely increased for PPP in multi-GNSS as compared to the single GNSS. A continuous decrease in percentage along with prolonged timespan for PPP convergence was observed with increasing cut-off elevation angle. However, the performance of multi-GNSS PPP, which was superior to that of the single GNSS, shows that it is extremely valuable for practical applications in mountainous or sheltered areas.