Low-temperature heat source heating represents a pivotal technological direction for global energy decarbonization and building heating decarbonization. Its development is deeply integrated with fourth-generation district heating (4GDH) concepts, forming a comprehensive technical framework encompassing top-level design, pipeline systems, terminal equipment, and standardized modeling. This study systematically reviews research advancements in low-temperature heating technologies across conceptual frameworks, network performance, economic viability, intelligent control systems, terminal innovations, thermal comfort, and standard methodologies. It highlights core advantages of low-temperature heating systems in reducing heat and exergy losses, integrating renewable energy and industrial waste heat, and enhancing system flexibility. Research demonstrates that low-temperature district heating networks exhibit significantly superior energy efficiency and cost-effectiveness compared to traditional high-temperature systems. Existing building retrofits require shorter investment payback periods, optimized terminal equipment can reliably adapt to low-temperature operating conditions, and intelligent control coupled with demand response mechanisms further reduce operational costs. Future technological priorities will focus on low-cost deep retrofitting, cross-sector energy integration, market-based incentive mechanisms, and standard upgrades to provide critical support for clean heating initiatives and carbon neutrality objectives.