Abstract: Vibrations usually cause harm to the people and objects around them. However, installing non-damped dynamic vibration absorber on the vibration body is one of the measures to effectively control the vibration. Service condition for a non-damped dynamic vibration absorber is that its natural frequency needs to be equal to or very close to the excitation frequency of the vibrating body. In this article, a new structure and theory for a dynamic vibration absorber with continuous adjustable natural frequency is proposed. Inside the steel rectangular frame without covers at the front and rear, two diagonal springs are symmetrically installed. The upper ends of two springs can be moved symmetrically along the upper surface of the frame, and the same spherical mass block is suspended from the lower ends of two springs. Quantitative change relationships between horizontal displacement of upper end of spring and angle between spring and vertical direction, between total vertical stiffness of springs and angle between spring and vertical direction, between total vertical stiffness of springs and horizontal displacement of upper end of spring are established theoretically. Meanwhile, the vibration control effects of this dynamic vibration absorber are experimentally verified. This is used to provide a new reference for the design of dynamic vibration absorber.