Pneumatic conveying type seed metering device and seeding system

The present invention relates to the technical field of agricultural machinery equipment, and provides an air-assisted seed-metering device and a seeding system, the air-assisted seed-metering device comprises: a pointing seed injection device, the pointing seed injection device comprises a seed injection pipe and a sensor, and the sensor is suitable for detecting whether seeds pass through the seed injection pipe and generating and sending a detection signal; the loop seed injection device comprises a plurality of seed injection ports which are uniformly distributed into an annular structure, every two adjacent seed injection ports are arranged at a preset angle, and the outlet end of a seed injection pipe faces the seed injection ports and can rotate around the central axis of the annular structure; the rotary driving part is used for driving the outlet end of the seed injection pipe to rotate; the controller sends out a control instruction when it is judged that the seeds pass through the seed injection pi