A conventional calibration of size exclusion chromatography (SEC) requires a set of narrowly distributed polymer standards with different molecular weights (M)．In this study，a novel method was proposed，wherein the intrinsic co-nnection between the measured retention volume (V) in SEC and the diffusion coe-fficient (D) in dynamic laser light scattering (LLS)，i.e.，both v and D are related to the same hydrodynamic volume．is utilized to calibrate both SEC and DLS in a single process by using only ONE broadly distributed polymer sample．One broadly distributed polymer standard (NBS706) was used in this study to verify this propo-sed method．The calibration between v and M from this method is fairly comparable to that from the conventional method，and the calibration between D and M is also in agreement with the literature values． With these two calibrations，both of the conversions from the retention volume distribution in SEC and diffusion coefficient distribution inG(D) to molecular weight distribution have been accomplished．This novel method will enable US to use SEC to characterize special polymers where the conventional SEC calibration is not applicable．