The invention provides a rice DPS1 gene and encoded protein and application thereof. The sequence of the rice DPS1 gene is shown in the SEQ ID No.2, and the sequence of the encoded protein is shown in the SEQ ID No.1. It is found that the top spikelet of the mutant of the rice DPS1 gene is dry up and necrotic before flowering, and the middle spikelet closely adjacent to the top degenerated spikelet is sterile, which results in a significant decrease in the seed setting rate and the grain number per spike. The wild DPS1 gene is transformed into the rice DPS1 mutant, the degraded phenotype of the mutant spike top can be recovered, the result suggests that the DPS1 gene directly controls degeneration of the rice spike top by regulating programmed cell death, and the rice DPS1 gene can be applied to the directional design of rice spike types and used as an important genetic resource, is helpful to develop molecular markers in molecular breeding practice for conducting early identification and elimination on spike top degradation, and has important guiding significance for improving the rice yield.