Objective　To measure the relevant distance between the superior nuchal line, inferior nuchal line and the foramen magnum,  and provide the clinical application with scientific and reasonable data.　Methods　The following points in 113 cases of normal and dry skull specimens of Chinese adults were selected: the highest point of the external occipital protuberance and points 1cm and 2 cm left and right on the superior nuchal line; the middle point of the occipital crest and points 1cm  left and right on the inferior nuchal line. Straight lines from those selected points to the foramen magnum parallel to the skull posterior median line were drawn. Measure of the arc distance, straight distance, vertical distance and horizontal distance between the superior nuchal line and the inferior nuchal line,the superior nuchal line and the foramen magnum, the inferior nuchal line and the foramen magnum were made with an ordinary vernier caliper.　Results　The distance between the superior nuchal line and the inferior nuchal line was minimum in the posterior median line. The values of its straight distance, arc distance, vertical distance and horizontal distance were（18.11±2.99）mm,（19.18±2.83）mm,（11.11±3.44）mm and（14.65±3.19）mm respectively. The horizontal distance to the left or right diminished, but the other distances increased.  The distance between the midpoint of the occipital crest and the foramen magnum was minimum. The values ofits straight distance, arc distance, vertical distance and horizontal distance were（21.73±3.35）mm,（22.74±3.47）mm,（10.69±3.44）mm and （19.10±3.35）mm respectively. The distances to the left or right lengthens increased.　Conclusion　The location of the inferior nuchal line is the key to ensure the safety and effectiveness of clinical practice. It can determine the location of the nuchal line with the help of the external occipital protuberance and the superior nuchal line. In the posterior median line, the distance between the superior nuchal line and the inferior nuchal line is minimum, and the number is (11.11±3.44)mm.