The study utilizes soliton microcombs with hybrid PolSK-OAM modulation for spatial mode multiplexing in free-space optical communication systems (FSO). To achieve this, we use a microring resonator to generate soliton microcombs, with information modulated using the PolSK format. The carrier beam is subsequently transmitted through a spherical phase plate to impart an OAM mode suitable for spatial multiplexing. The results show significant improvements, achieving a bit error rate (BER) of \(10^{-5}\) at a signal-to-noise ratio (SNR) of 25 dB, and a channel capacity of \(1.8 \times 10^4\) over 9 km, surpassing traditional systems at \(1.4 \times 10^4\) . The system supports more simultaneous transmissions without additional bandwidth, thus meeting the demands of next-generation networks. It also exhibits a low outage probability ( \(<10^{-8}\) ), enhancing reliability, availability, and reducing latency. Additionally, the system offers improved energy efficiency as well as enhanced spectral efficiency, allowing for greater data transmission within the existing bandwidth, promoting the sustainability of telecommunication infrastructures, thereby reducing greenhouse gas emissions and environmental impact.