A new shape contour description method based on eight-direction chain code and fast Fourier transform(FFT) is proposed.Firstly,the chain code tracks the shape boundary sequentially according to the relationship between contour and chain-code projection-transform value.A constructed chain-code function of contour is transformed using FFT.After optimization,then a new Fourier constant factor descriptor(FCFD) is proposed.The descriptor is independent of the initial point and has rotation,scale shift and(RSS) invariant properties.The results of experiments show that our shape contour description method has the RSS proerty and is non-correlative with the initual state.It reduces the computation and improves the efficiency of data processing effectively.