The invention discloses a sampling part. The sampling part comprises a sampling body and an insulating handle, wherein the sampling body can be electrified and heated, and the external surface of the sampling body is provided with a wiping sampling area; and the insulating handle is connected with the longitudinal end of the sampling body. The sampling part is directly contacted with the contact of an external power supply after being embedded into an analysis cavity, and is connected with the power supply to heat the sampling body so as to realize sample analysis, and electricity is immediately cut off when the sampling part is taken away. Therefore, the power supply of a sample injector can intermittently work, the power consumption of a system is reduced, and the system can be prevented from being failed due to the long-term high-temperature work of a sample injection device simultaneously. The invention also discloses the sample injection device with the sampling part and an ion mobility spectrometer with the sample injection device.