The invention provides a modeling method for zenith tropospheric delay. The modeling method comprises the following steps: S11, obtaining a zenith tropospheric delay amount actually measured in each observation station; S12, calculating an annular mean value ZTDh of the zenith tropospheric delay amount corresponding to the observation station, fitting based on ZTDh to obtain an elevation correction coefficient beta and an annular mean delay amount ZTD0 naturalized to an ellipsoidal surface, corresponding to the observation station, and obtaining a single-day delay amount ZTD0(doy) after elevation correction, corresponding to the observation station according to the beta; S13, fitting based on ZTD0(doy) to obtain a period constant term A0, amplitude and initial phases A1 and d1 of an annual periodic term as well as amplitude and initial phases A2 and d2 of a semi-annual periodic term, corresponding to the observation station; S14, building a latitude and longitude grid function model based on the Chinese mainland area, and calculating based on the parameters A0, A1, d1, A2 and d2 corresponding to the observation station to obtain A0, A1, d1, A2 and d2 corresponding to each grid point in the grid function model. The modeling method is suitable for the Chinese mainland area, the precision is remarkably improved, and the overall service level of a satellite navigation positioning system of the Chinese mainland area can be improved.