Kinematics model of mechanical hydraulic system usually involves the speed, acceleration and geometric constraint, which will contain one or two and even higher order differential equations. The number of differential-algebraic equations (DAEs) increases with the increase of system complexity. In order to find a suitable control arithmetic, it is needed to figure out the relationship of different state variables. However, it’s always impossible to get analytical solution. Thus it is needed to find the numerical solution of DAEs system, especially when it has too many state variables. Solving this problem with computer software is a common way; there are several helpful softwares, such as Matlab, Maple, Simulink and Mathematica. The mathematical function provided by the Matlab ode45 was used to solve the kinematics model of leveling system of paddy field leveler with sinusoidal input current. Firstly, the real paddy field leveler was simplified to kinematics model and showed in DAEs form based on theoretical mechanics and hydraulic theory. Secondly, the DAEs were changed into ODEs (ordinary differential equations). Finally, the ode45 was used to get numerical solution and show the relationship of state variables. The input current and output state variables were showed in figure. The method can help to get accurate numerical solution for DAEs system, and it also can display the relationship between the random input with known equations and other state variables. It will help to forecast the state variables at the next moment and design an efficient control algorithm for paddy field leveler.