In order to make the electromechanical actuator have the ability to adapt to the irregular installation space of high speed aircraft and the great dynamic characteristics, an adjustable actuator based on slider-crank structure was proposed and its transmission characteristics were studied. Firstly, the uniform nonlinear transmission ratio model is obtained respectively by applying speed synthesis theory and structure force balance theory. Secondly, the optimal layout of best symmetry is obtained by mathematical analysis. Then, the computer aided model was established, and the correctness of the nonlinear model was verified. Finally, the dynamic properties of the structure forms are simulated using MATLAB software, and compared with the existing fork structure and rocker arm structure. The simulation results show that, the actuator with slider-crank structure has great dynamic performance and strong adaptability to space, which is even more suitable for the requirements of high speed aircraft.