As the second most abundant element in the Earth crust after oxygen, the transfer and transformation of silicon (Si) are one of the most important processes of soil formation and evolution. Biological processes are known to play significant roles in soil formation and mineral weathering. Especially, plants can take up dissolved silicon (DSi) and deposit it to produce silicified structure as phytolith, a kind of biogenic silicon (BSi). In this paper, a chronosequence including seven basalt-derived soil profiles in northern Hainan Island was studied. The extraction of BSi was conducted following a wet extraction procedure, in which heavy liquid of ZnBr₂ (2.35 g cm_-3) was used to separate phytoliths from other heavy mineral fractions. Results showed that contents of BSi in the soils varied widely from 2.9 to 54.0 g kg^-1. The highest concentration of BSi occurred in the surface horizon of profile HE09, a young soil on basalt, while the lowest was found in the B2 layer of HE11, an older soil in the sequence. In general, the contents of BSi, OC and TN are high in the surface horizon of soil profiles and decrease rapidly with depth. This phenomenon is prominent in topsoil, especially from surface to 40 cm. The finding implies that the accumulation of BSi in topsoil is mainly due to BSi release from organic matter during its decomposition. During soil development, these soils became progressively more weathered, with base cations depleting, clay fraction increasing and pH decreasing. Furthermore, a linear correlation between BSi and TSi was found for all soil samples, indicating that BSi determines to a certain extent the whole Si cycles during soil development. In the initial stage of soil development, DSi from weathering of primary minerals may contribute to the conservation of BSi, while with time, continuous high rainfall and depletion of cations leads to leaching or recycling of BSi faster than plants can bring it to the surface. As a result, the contents of BSi may maintain a relatively stable state with the function of biogenic pump in the soil-plant system. In conclusion, BSi is playing a very important role in tropical soil formation and evolution, especially in the biogeochemical cycles of Si.