The spring elastic coefficient is accurately measured based on the principle of ultrasonic ranging and lever amplification. The device uses an ultrasonic measuring system to accurately measure the expansion length of the spring amplified by the lever principle, and uses the method of pulling the spring up vertically to eliminate the influence of spring gravity on the experiment, so as to accurately determine the deformation and elastic coefficient of the spring. The experimental device is a new device for measuring spring elasticity coefficient accurately. It has the advantages of small measurement error, simple operation and strong intuition. It can be used not only as a device for measuring spring elasticity coefficient accurately, but also as a teaching demonstration device for classroom teaching to stimulate students' interest in physical experiments.