Abstract: With the development of the Global Navigation Satellite System (GNSS), the channels and frequencies used for precision point positioning (PPP) are gradually diversified. Therefore, based on the original observation equations, this study derived the dual-frequency ionosphere-free (IF) PPP model for differential code bias (DCB) and observable-specific signal bias (OSB) products, respectively, and used 10-day continuous observation data collected from 50 Multi-GNSS Experiment (MGEX) stations to analyze the performance of the PPP model for each GNSS system. The results show that the performance of PPP model using the OSB product is consistent with that of the conventional DCB product, and the OSB product is more convenient to use and has more applications in future multi-frequency PPP.