Network Real-Time Kinematic (NRTK) are mainstream technologies for real-time centimeter-level positioning based on Global Navigation Satellite System (GNSS). Tropospheric delay, as a major error source in Real-Time Kinematic (RTK) positioning, is particularly significant in medium to long baseline positioning. Based on the NRTK method, utilizes GNSS sample data from four reference stations to estimate Zenith Tropospheric Delay (ZTD), ambiguity and position parameters through double-difference processing. Innovatively, prior interpolated ZTD is introduced as an observation value, effectively enhancing positioning accuracy and Integer Ambiguity Resolution (IAR) performance. ZTD interpolation data from the International GNSS Service (IGS) reference station network is employed, combined with the Weighted Least Squares (WLS) method for solution. Experimental results indicate that, compared to traditional RTK methods with unknown ZTD, the technique achieves an IAR success rate of nearly 100%.