The present invention discloses a grain germinating system comprising a temperature controlling device, an incubation device, a drying device and a monitoring device. The temperature controlling device comprises a heat pump module, an air conditioning module and a piping module. The heat pump module can output a high or low temperature heat exchanging liquid. The temperature of a culture medium of a grain is adjusted by the incubation device. The incubated grain is dried by the drying device. The air conditioning module is for a plant building. The piping module is connected with the heat pump module, and is provided for the high or low temperature heat exchanging liquid to flow. The incubation device and the drying device are heated by the high temperature heat exchanging liquid. The drying device is cooled by the low temperature heat exchanging liquid provided for the air condition of the plant building to use.
