<p>The establishment of the global quantum communication network relies on the effective integration of free-space links and optical fiber networks. Mode-pairing quantum key distribution (MP-QKD) represents an advancement in measurement device-independent quantum key distribution (MDI-QKD). By eliminating the need for a complex light-field setup, it breaks the rate–distance limit and can be theoretically applied to the light-field setup of free-space MDI-QKD. In this work, we propose a mode-pairing quantum key distribution model that integrates satellite-based links and fiber links, and its performance is analyzed by simulating the probability distribution of atmospheric transmittance (PDT) between satellites and ground stations. Additionally, the effects of pairing interval and misalignment error are discussed. This work may provide some important references for the future widespread application of satellite-to-ground multipath quantum key distribution.</p>