In order to realize water management target of male parent in shallow water and female parent wetted under the planting mode of “mechanical transplanting of male parent at the bottom of ditch + direct-seeding of female parent on ridge platform”, a ditching device was designed for 2ZD-2.4 type transplanting in ditch and seeding in ridge hybrid rice breeding machine, which was composed of seed ditch opener, water storage ditch opener, rice transplanting ditch opener and floating plate. The floating plate drives the ditch opener to open the required groove synchronously. Through the mechanical analysis, the effects of the soil angle, element line angle of ditching device and length of extrusion molding surface on the ditching performance were investigated using three factors and three levels orthogonal test. The multi-objective optimization was conducted to obtain the optimal parameter combination of the ditch opener. The results indicated that when the soil angle of 5°, the element line angle of 65°, and the length of the extrusion molding surface of 140mm, the soil reflux rate of sowing ditch and the stability coefficient of ditching depth were 10.99% and 8.34%, respectively. The sowing ditch, water storage ditch and seedling transplanting ditch were accomplished simultaneously through ditching device. Field experiment results showed that both the leakage rate and dumping rate were lower than 2.0% and germination rate of female parent was 87.67% when the depth of transplanting ditch was 50 mm and the depth of transplanting was 22.8 mm, which can meet the agronomic requirements of hybrid rice seed production and planting.