<p>Phylloid algae are the dominant reef-building organisms during the Pennsylvanian, and they have a widespread distribution. However, the construction model and the controlling factors of the phylloid algal reef during this period were not well understood. In this study, a well-developed Kasimovian triple hybrid carbonate reef is reported for the first time from the Houchang area, southern Guizhou Province, South China. The reef is primarily composed of phylloid algal cementstones and phylloid algal-cement-microbial framestones. The reef developed in a platform margin setting within the photic zone under well-circulated marine conditions, likely around the fair-weather water base. Phylloid algae, abiotic cements and microbially mediated cements were dominant contributors to the studied reef. Phylloid algae could build simple frameworks. Early marine cement stabilized the reef framework and filled almost half of primary cavities. Microbial carbonates occurred in the upper part of the reef, as subordinate framework stabilizer. This phylloid algal-cement-microbial reef is classified as a triple hybrid carbonate in the tropical region of eastern Paleo-Tethys. It was controlled by long-term and regionally universal factors throughout the Pennsylvanian, including eustatic fluctuations, atmospheric <i>p</i>CO₂ levels, and seawater chemistry (specifically the Mg²⁺/Ca²⁺ ratio). The studied reef provides insight for the triple hybrid carbonates in the Late Pennsylvanian.</p>