The precision seeding method of rice with cavity-type has the advantages of simplifying the seeding mechanism and reducing seed damage. Aiming at the problem of miss-seeding holes during the hill-drop direct seeding process of the cavity-type precision and small-amount seed-metering device of hybrid rice, combining with the method of combined pulse, a novel loss sowing detection method and its supporting system with cavity scanning of light curtain was designed based on cavity-type seeding principle. The construction method of combined pulse was expounded and the dynamic model of rice seed movement in the cavity detection zone was established to clarify the key structural parameters of the cavity. Subsequently, the performance tests of the loss sowing detection system at different rotational speeds, variable rotational speeds, and different vibration conditions of the seed-metering device were carried out successively. The results of the rotational speed adaptability test showed that all the detection errors at different rotational speeds and variable rotational speeds of the seed-metering device were not higher than 0.80%. The results of the vibration adaptability test showed that the performance of the detection system was not affected by the medium and high-frequency vibration conditions, while affected by the low-frequency vibration conditions characterized by relatively large amplitude with slightly larger detection error, but the error was not higher than 1.20%. The field test results showed that the detection system had good adaptability to different forward speeds of seeder, and the detection error was not higher than 2.13%. The research result can provide a theoretical reference for loss sowing detection method of rice precision and small-amount seeding, and lay the foundation for the development of reseeding systems.