An automatic height profiling device with spring force-balance is designed to solve the problem of ground profiling in side-lining type of quadrate-bale baler pickup. Based on the analysis of statics and kinematics to the profiling device, the profiling performance is evaluated by the vertical direction force of profiling wheel and the profiling error. The effects of the kinematic parameter (λ) of pickup, the length (L) of the swimming arm and the amplitude (H) of the ground on the profiling performance are analyzed. The appropriate pickup movement parameters and profiling device structure parameters are determined by making a comparative analysis on the profiling error of the end of spring-finger and vertical direction force of profiling wheel. These results show that the profiling device can fulfill the requirements of a wavy terrain which varies between ± 8cm and ±12cm, when the unit speed (vt) moves from 5km/h to 7.9km/h and the length (L) of the swing arm of profiling wheel is 358mm. The prototype test shows that the profiling device can adapt to wavy field and make the spring-finger of pickup have suitable ground clearance. The profiling error can be controlled between -4mm and 18mm.