The invention discloses protein OsPPR5 for controlling grain thickness and thousand-grain weight of oryza sativa and a coding gene and application of the protein OsPPR5. The amino acid sequence of theprotein is as shown in SEQID NO.1. The OsPPR5 protein provided by the invention has the effects of positively adjusting and controlling the grain thickness and the thousand-grain weight of the oryzasativa, can be directly applied to actual production, is used for increasing the thousand-grain weight and the yield of the oryza sativa, and does not influence grain length and grain width, and a bran-new genetic resource is provided for basic research and breeding utilization of the grain type and the thousand-grain weight of the oryza sativa.