Current methods for finger valley point extraction are for hand images under higher placement requirements.Once the images placed are not strictly adhered to requirements,valley points can not be correctly extracted.So an extraction method for finger valley points under natural state is proposed in this paper.Firstly,identify t he detection column of the image which can cross four fingers(forefinger,middle finger,ring finger,little finger) and make out the gradient image of detection column,and then locate the finger edge points by extracting four peak points and four valley points of the gradien t image;according to the distances between every two adjacent fingers,the states that whether are closed or open can be adjusted;la st,according to the states,corresponding line tracing methods:Roof tracing or Step tracing,are adopted to tracing lines,and the tra cing end points are the corresponding finger valley points.Besides,this method based on gray image can avoid image binarization an d contour extraction operation,improving the running speed of this algorithm.A self-built image database is used to test th is algorithm,and the correct extraction rate is 97.14%, proving it feasible and effective.And this method can avoid the impact of finge rs′ opening degree,proving it superior.