Rydberg atoms, distinguished by their exceptionally large electric dipole moments and polarizabilities, have emerged as a compelling platform for microwave electric-field quantum sensing, offering promising prospects in metrology, wireless communication, and radar detection. Nevertheless, a persistent gap separates the high-sensitivity microwave detection capabilities of Rydberg atoms from practical engineering deployment—most notably, the ability to receive weak signals over long distances remains to be fully validated. Here, we develop a miniaturized Rydberg atomic microwave receiving prototype based on a cesium ladder-type three-level system, in which heterodyne detection is synergistically integrated with microwaveresonator local-field enhancement. We successfully demonstrate microwave signal reception over a distance of 20 km in an outdoor, real-world environment. The experiment employs a 3.785 GHz microwave link, with the transmitter and receiver stationed on two hilltops approximately 20 km apart. By mixing the signal with a local oscillator field inside the atomic vapor cell to generate an intermediate-frequency heterodyne beat signal, the system attains a signal-to-noise ratio of 20 dB at a resolution bandwidth of 5 Hz, corresponding to a microwave detection sensitivity of -134 dBm/Hz. This work not only validates the long-distance operational capability of quantum sensors in complex outdoor environments but also provides an important experimental foundation and reference for developing quantum-based remote communication, radar detection, and spectrum monitoring technologies.