There exists a large amount of rice straws before rapeseed planting operation in the middle and lower reaches of the Yangtze River due to the special ricerapeseed rotation farming system, making it hard for conventional planter to operate all the planting process in one time, even the slipping and sinking of the tractor will happen if the moisture content of the soil is high. On the other hand, the combine harvester, which has better passing ability, stays idle after harvesting, leading to a relatively low utilization rate. As a solution, a planting scheme that can simultaneously realize rice harvesting and rapeseed planting was put forward, and a rapeseed direct seeder on tracked combined harvesting power platform was designed. During the operation, the straws would be collected by the harvester platform in advance while the rotary tillage and planting process would be conducted by the planter behind the harvester. The combine planter could complete all the processes like the straw return, seedbed rotary tillage, seedbed furrowing and seed covering in one time without any pretreatment of the rice straws in the field. In more detail, the grail-mounted suspension lifting system was designed, and the static analysis was carried out based on ANSYS Workbench and Matlab optimization toolbox. In addition, the strength of the suspension lifting system was verified and the chain drive parameters were optimized to determine the structure and parameters of key components. Furthermore, the longitudinal stability of the planter was analyzed, and the reserve utilization coefficient of longitudinal stability was 0.198 which was in line with the requirements of tracked unit quality configuration. At last, the field experiment was conducted. The tillage depth stability, soil fragmentation rate, qualified rate of rotary tillage layer depth, passability and work stability were considered to be the indicators. Under the working conditions of straw retention and high soil moisture content, the results indicated that the passability and work stability of the planter were better when the working speed, engine speed and fan speed were 0.6m/s, 2000r/min and 3500r/min, respectively. The stability coefficient of tillage depth and the qualified rate of rotary tillage layer depth were both over 90%, and the soil fragmentation rate was 83.7%, which could meet the agronomic requirements of rapeseed planting directly on the surface of rice after harvesting in rice-rapeseed crop rotation areas.