The binding of lotus seedpod oligomeric procyanidins (LSOPC) and catechin (a major constituent unit of LSOPC) to bovine serum albumin (BSA) was studied by a fluorescence quenching technique. The results revealed that LSOPC could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure, but catechin could not. The Stern–Volmer quenching constant, K SV, and corresponding thermodynamic parameters, ΔG 0, ΔH 0 and ΔS 0, were calculated. The results of synchronous fluorescence and circular dichroism studies showed that LSOPC could cause a conformational change in BSA. In addition, glucose and metal ions could affect the interaction between LSOPC and BSA.