In this paper an algorithm for detecting blood vessel shape in image of digital subtraction angiograph(DSA) base on mathematical morphology is proposed. In the first step of the proposed algorithm

the central line of the designated blood vessel can be detected by means of matched filter and adaptive tracking

and then the edge of the blood vessel is extracted by using erosion gradient operator. The performances of dilation gradient

Beucer operator and VVL operator are also discussed. The experimental results show that the proposed method has important value for clinic application. The method can be used directly for detecting blood vessel in DSA image without smoothing DSA image

so that some useful information of blood vessel can be preserved and the high precision of edge detection can be achieved without any strict restraint on the shape of blood vessel.