N-Ethyl chitosan (NECS) with degree of substitution 0.94 was prepared from chitosan and acetaldehyde．The films of NECS were prepared via the solution casting technique using formic acid as solvent．The crystalline structure and crystallization process were investigated by means of polarized optical microscopy

scanning electron microscopy and X-ray diffraction．Thousands of needle-like crystals

which are seldom found in polymers

were observed in NECS cast films after few days casting. The needle-like crystals were formed from spherulites through a psot-crystallization process．The shape of needle-like crystals was long rectangle with a typical size of ～50 μm(length)×2～5 μm(width)×1～2 μm(height)

and molecular chains are parallel to the long axis of the needles．The neddle-like crystals were first found on the centers of the spherulites．and then on every ioint of dendritical fibrils of spherulites

at last on everywhere of spherulites．Generally speaking

the needle-like crystals basically oriented at the direction of radius of spherulites(also the direction of molecular chains) and decorated the sphrulites．The possibility of post-crystallization was explained by the results that the cast films became super-concentrated solutions(＞80％)after the adsorption of moisture because of the hydrophilic properties of NECS. The remained solvent and absorbed water were used as plasticizers

which increase the mobility of polymer chains. The dendritic crystals consisted of needle-like crystals were also found in the systems．