Abstract: N,N–dilauryl chitosan/PLLA (NCS/PLLA) blend membranes with three different compositions were prepared by solution approach using CHCl3 as cosolvent. The hydrogen-bonding interactions between NCS and PLLA were studied with FTIR，TA and WAXD methods. FTIR experiments indicated that the wave numbers of hydroxide stretching band of NCS and the carbonyl stretching band of PLLA in the blend membranes had a red-shift change compared with both pure materials. TA results confirmed that the thermal stability of the blend membranes was higher than that of NCS alone，the Tm and crystallinity of PLLA in blend membranes decreased compared with pure PLLA. WAXD patterns showed that the crystal peaks of PLLA at 2θ=16.7°，19.1° shifted to a lower angle，and the diffraction peak beca me weaker and broader obviously in the blend membranes with increasing NCS content，even disappeared when NCS content reached 50%. SEM images of blend membranes showed that good miscibility existed in this blend systems. The most interesting and important finding of the present study was that the miscibility of the NCS/PLLA blend systems mainly came from hydrogen-bonding interactions between the hydroxyl groups of NCS and the carbonyl groups of PLLA.