Abstract: With the development of since and technology,the directional device,like high precision electronic compass and gyro north finder,is miniaturized,practical and portable.The using of North finder used in setting up the seismic instrument became possible,and obtains good results.But now,the method of directional line drawing of north finder is still relatively primitive,so the efficiency of directional line drawing is not high.The efficiency of orientation line drawing will be improved greatly by using the auxiliary device of north finder design and optimized directional line drawing method.