  Satellite-to-ground quantum communication constitutes the cornerstone of the
global quantum network, heralding the advent of the future of quantum
information. Continuous-variable quantum key distribution is a strong candidate
for space-ground quantum communication due to its simplicity, stability, and
ease of implementation, especially for the robustness of space background light
noise. Recently, the discrete-modulated continuous-variable protocol has
garnered increased attention, owing to its lower implementation requirements,
acceptable security key rate, and pronounced compatibility with extant
infrastructures. Here, we derive key rates for discrete-modulated
continuous-variable quantum key distribution protocols in free-space channel
environments across various conditions through numerical simulation, revealing
the viability of its application in satellite-to-ground communication.
