Due to the low mechanization and standardization level of the vegetable seedling and the lack of germinated-seed assisted planting machine in the small and medium-sized seedling factory of China, a simple split-type substrate filling machine for factory vegetable plug-tray seedling was developed. It mainly included five parts: stirring sub-system, discharge subsystem, tray transmission sub-system, screeding sub-system and control sub-system. The test results showed that it can successively finish the pre-wetting stirring, discharging, plug-tray filling and scraping on the plug-tray, and further digitally display the temperature and humidity, pH and EC values of the pre-wetting seedling nursing substrate. When the diameter of the hole in the bottom of the discharge port was 34mm, the rotation speed of the double helical substrate-distributing roller was 80r/min, and the moving speed of the conveyor belt was 0.44m/s, the machine had the best performance in the plug-tray filling, reaching 99.05%. At this time, the filling efficiency was 300 plug trays/h, and the selected sensor can digitally show the temperature, humidity, pH and EC values of the substrate so that large quantities of standardized factory seedlings can be achieved.