In mountainous orchard of southern China,currently the selfloading devices with the Ltype pull arm were mostly put into use in leveling roads with large volume which is not suitable for the mountainous region. In order to protect the fruits and improve the transport efficiency,a selfloading device with the Ltype pull arm in mountainous orchard transporter was designed,and simulations were conducted. The stress of the Ltype pull arm was analyzed with the traditional graphical method to calculate the formula of main mechanical stress in the course of two campaigns,and the critical angle was 38 °. Getting the relation between the main part of power and the rotation angle by ADAMS. Results indicated that there were four cases regarded as dangerous conditions: slope of -20° and rotation angle of pull arm of 0°,slope of 20° and rotation angle of pull arm of 38°,slope of -20° and rotation angle of pull arm of 134°,slope of -20° and rotation angle of pull arm of 38°. Results of ANSYS finite element analysis declared that most of stress of the pull arm was in the range of 0.0768.316 MPa. The maximum stress was 307.144 MPa,less than 470 MPa of the steel Q345’s minimum tensile strength. This design has met the demand to complete the requirements of loading and unloading on the working conditions that the slope of 15° and the load of 150 kg.