Abstract: As an important characterization parameter of cancellous bone microarchitecture,mean trabecular bone spacing (TbSp) serves as an important index for osteoporosis diagnosis.An estimation method for TbSp,quadratic transformation method QT),was introduced.The superiority of this algorithm was approved by scatter simulation,finite difference time domain (FDTD) numerical simulation and in vitro experiment with cancellous bone specimens of bovine tibia,compared with four existing methods,auto regressive cepstrum (AR),adaptive filter-autoregressive cepstral (AFAR),inverse filter-auto regressive cepstrum (InvAR),simplified inverse filter tracking (SIFT) algorithms.The results of the simulations and experiment indicate that QT is much more stable and accurate than the other four existing methods.