Phosphorus (P), one of the most important nutrients in soil, is essential for plant growth, and plays a significant role in maintaining the balance of forest ecosystems. Furthermore, soil P availability is controlled mainly by geochemical and biological processes and can be vulnerable to global climate change. Warming, which has become one of the most important topics of current study, directly and indirectly alters soil P cycling in terrestrial ecosystems; however, to date, most studies have focused on nitrogen deficiency in temperate ecosystems, and have produced inconsistent results regarding the responses of soil P dynamics. Few relevant studies have been conducted in P-deficient tropical and subtropical forest ecosystems. In order to study the potential impacts of warming on soil P fractions related to P availability, we simulated warming in a subtropical Chinese fir plantation, and undertook sampling after one and a half years of short-term warming. The result showed that soil acid phosphatase in the warming treatment was 1.5 times higher compared to that in the control treatment, and that soil available P had increased by 25%, whereas soil total P, microbial P, and organic P had declined by 6%, 34%, and 12%, respectively. The increased soil P availability after short-term soil warming is mainly attributed to an increase in acid phosphatase activity that can promote mineralization of soil organic P, and to the reduced P immobilization of microbe. Despite the increase in soil available P after short-term warming, the significant decrease in microbial P, which is potentially available for plants, is likely to exacerbate P limitation in subtropical Chinese fir plantations. The findings of this study indicate that more attention should be paid to the responses of soil P to climate warming in the subtropical zone and highlight the need for further research.