Due to the characteristics of measurement datum distribution, the altitude positioning error of GPS (Global Positioning System) is relatively large. This study discusses a differential barometric altimetry (DBA) system from systematic implementation level and provides a key technical solution for the continuous and precise altitude measurement from the DBA systematic implementation aspect, which can provide a good supplement and enhancement for GPS. The structure of signal message is designed; the power spectrum of spread spectrum ranging signal is given, and the fusion of navigation and communication is realised. The two dimensional curved surface fitting function of pressure and temperature (P, T) is constructed, and the fitting parameters are calculated by the least-square solution, which can realise calibration compensation and measurement correction of sensor. The influence of the system noise variance matrix Q _k and the measurement noise variance matrix R _k on the filtering effect in Kalman filter is analysed. An algorithm of multi-base station (BS) correction is proposed, which can realise the height information correction calculation in measuring station (MS) via seamless handover between multi-BSs. The experimental results show that the key technology solutions in DBA system can achieve a well systematic performance..