The invention discloses an I-129 sampling device and a sampling method. The device includes a sampling pipeline unit and a sampling detection unit; the sampling pipeline unit includes a sampling gas inlet joint, a purge gas inlet joint, a sampling gas outlet joint, and a sampling gas Intake pipe, purge gas inlet pipe and sampling gas outlet main pipe; the sampling gas inlet pipe is provided with a first filter, a first stop valve, a first flow meter, a first electromagnetic reversing valve and a first regulating valve, and the purge The gas inlet pipe is provided with a second filter, a second stop valve, a one-way valve, a second flow meter, a second electromagnetic reversing valve and a second regulating valve. The sampling detection unit includes a first iodine sampler, a second iodine sampler and an iodine detector. The device of the invention has a simple structure, can effectively remove the influence of Kr-85 on I-129, and at the same time realize high-efficiency sampling of I-129, has good application effect and is easy to popularize.