The leveling of paddy fields is an indispensable part of rice production. Aiming to improve the adaptability of existing leveling machines to the bumpy hard bottom layer of paddy fields and further enhance the operational performance, the supported paddy-field leveling implement was developed. Firstly, according to the working principle of the leveling shovel, the height adjustment mechanism of the leveling shovel was kinematically analyzed. On this basis, the leveling shovel and its height adjustment mechanism were designed. Secondly, the supported rod structure was designed, and the influence of the supported rods on the motion characteristics of the leveling shovel was studied. Finally, a comparison test with / without supported rods and a paddy-field leveling test were carried out. The results of the comparison test showed that the amplitude of height change of the leveling shovel with the supported rods was reduced by more than 15% throughout the test, and reduced by more than 30% in the convex position of the field surface. Meanwhile, the number of height changes of the leveling shovel was reduced. It showed that the leveling shovel with supported rods was more conducive to the height control of leveling shovels and was more suitable for the operation of bumpy hard bottom layer of paddy fields. The leveling test results for 0.21 hm2of paddy field showed that the standard deviation ( Sd ) of the topography height was 21.66 mm, and the proportion (ρ) of points ( | hi - h | ≤30 mm, where hi indicated the height of each measuring point, and h indicated the average height of all measuring points. )was 86.54% . The test results for two paddy fields with a total area of 1.89 hm2showed that the standard deviations Sd for the two fields were 26.02 mm and 27.43 mm, and the proportionsρ were 80.53% and81.03% , respectively. After leveling, the standard deviation Sd in all test fields was less than 30 mm, and the proportionρ was higher than 80% , which met the requirements of paddy-field leveling, and verified the structural advantages and design validity of the supported paddy-field leveling machine. This can provide equipment support for mechanized leveling of paddy fields with bumpy hard bottom layer.