Tissue engineering is a new regenerative and medicinal concept which applies the principle and technologies of life science to construct a biological tissue or device to repair or reconstruct the structure of the tissue and organic in order to maintain and improve their function. An ideal scaffold should have the following characteristics : non-toxicity , biocompatibility ,suitable mechanical strength , biodegradation rate can match the rate of tissue regeneration and the biodegraded products should not have negative effects on the surrounding tissue and organs.