Soil phosphorus and its forms play a crucial role in farmland fertilization management and optimizing phosphorus utilization efficiency. This study focused on four climate regions in eastern China (mid-temperate, warm-temperate, subtropical, and tropical zones) to analyze the content characteristics of total phosphorus (TP), available phosphorus (Olsen P), and microbial biomass phosphorus (MBP) under different land use types (forest land, dry land, and paddy fields). The results revealed that soils in the warm-temperate zone had relatively high TP but lower Olsen P and MBP, likely due to phosphorus fixation under high pH conditions. In contrast, soils in the mid-temperate and tropical zones exhibited lower TP but higher Olsen P, attributed to high organic matter content in the mid-temperate zone and enhanced phosphorus transformation under high temperature and humidity in the tropical zone. Subtropical soils had the lowest TP and Olsen P levels, possibly due to heavy rainfall and fixation by soil iron and aluminum oxides. Across land use types, farmland soils generally had higher TP, Olsen P, and MBP compared to forest soils. In the mid-temperate zone, paddy fields had higher Olsen P but lower MBP than dry lands; however, no significant differences were observed between paddy fields and dry lands in the warm-temperate zone. In the subtropical and tropical zones, dry lands showed higher Olsen P and MBP levels compared to paddy fields. Overall, dry land soils demonstrated greater phosphorus availability and microbial phosphorus assimilation. Environmental factor analysis indicated that soil TP, Olsen P, and MBP were significantly correlated with soil organic carbon, mean annual temperature, and annual precipitation. This study provides scientific insights for optimizing phosphorus management strategies for farmland in eastern China.