Planting depth consistency of rape is an important index to evaluate the transplanting quality, which directly affects the slow seedling period and the roots regeneration, and even the rapeseed yield. In order to improve the planting depth consistency of rape seedling combined transplanter, a hydraulic profiling system based on the profiling wheel height induction was designed. The simulated ground test in laboratory were conducted, and the test results showed that the track of the profiling wheel was consistent with the planter at different speeds. At the speed of 0.3m/s, 0.6m/s, 0.9m/s and 1.2m/s, respectively, the track change trend of copying wheel and planter was consistent with that of road surface, and the phase was delayed, the amplitude was decreased by 5.8%, 15.2%, 17.7%, 33.8% and 14.9%, 21.5%, 41.5% and 54.6%, respectively, and the phase difference was 0.0267s, 0.0119s, 0.0225s, 0.0366s and 0.182s, 0.1264s, 0.1278s and 0.1489s, respectively. Taking three factors of forward speed, planting unit weight and height difference value of ground as influencing factors, and the qualification rate of planting depth as the test index, the second orthogonal rotation combination design test of three factors and five level was conducted. The test results showed that the influence degree from strong to weak was: the planting unit weight, the height difference value of ground and the forward speed. The optimal parameter combination was modified. When the planting unit weight was 30kg, the height difference value of ground was 20mm and the forward speed was 1m/s, the qualification rate of planting depth was 90.27%. It was better than the standard value, indicating that the hydraulic profiling system can effectively control the planting depth and improve the consistency of planting depth.