Abstract: An electric structure is designed to adjust the desktop height level of a desk and is formed of a base frame on which two elevation seats are mounted. A desktop is fastened with the elevation seats such that the desktop is moved up and down along with the elevation seats. A pivoting rod is pivoted between the two elevation seats and is provided at two ends thereof with a gear which is engaged with one of two racks mounted on the base frame. The pivoting rod is driven to turn by a motor which is mounted under the desktop and is capable of turning forward or in reverse, so as to enable the desktop to rise or descend.