Using the Hedley sequential extraction method, the effects of biochar application rate on soil phosphorus (P) fractions of Cunninghamia lanceolata seedlings with a pot experiment were evaluated. Three biochar application rate treatments were performed with 0 (CK), 12 t/hm²(B₁₂), 36 t/hm²(B₃₆). Results indicated that the contents of total P (TP) and available P (AP) in B₁₂ and B₃₆ treatments were increased by 8.7%-26.0% and 24.0%-101.7% in relation to CK after 180 days, and the proportion of AP in TP also was significantly increased. Among P fractions, residual P represented 48.5%-51.1% of soil TP and 58.7%-68.3% of soil inorganic P. B₃₆ treatment significantly increased the contents of inorganic P fractions, and the proportion of labile P and moderately labile P as inorganic P forms, while significantly reduced the percentage of occluded P and residual P to inorganic P. The proportion of moderately labile P in total organic P was the highest, accounting for 69.3%-70.2%. Biochar application had no significant influence on the proportion of organic P fractions in total organic P, and B₃₆ treatment significantly decreased the contents of labile P and moderately labile P as organic P forms. Redundancy analysis revealed that soil total carbon was significantly positively correlated with soil inorganic P and negatively correlated with soil organic P, which was the key factor influencing the changes of soil P fractions.