The invention provides a satellite-ground cooperative in-orbit real-time geometric positioning method and system for optical satellites. The method comprises the following steps: an optical satellite imaging and positioning model suitable for an onboard real-time processing unit is constructed, initial values of onboard positioning model parameters are acquired by calibration parameters or design parameters for camera interior and platform installation relation by a ground laboratory, after the satellite is in orbit, ground calibration field image data is acquired and downloaded, calibration matching and calibration parameter calculation are completed in a ground processing system by using the downloaded calibration field images; calibration results are verified and model parameter annotation is updated. The method and the system aim at limitation of onboard processing environment, and combine the ground processing system, so that a satellite-ground cooperative processing mode is formed, in-orbit high-precision real-time geometric positioning of optical remote sensing satellite is realized, application usefulness and timeliness of earth observation systems are improved, and necessary bases are provided for intelligent and high-efficient remote sensing data onboard real-time processing technology.