The invention relates to a tobacco source heavy metal ion adsorbent and an application thereof. A preparation method of the tobacco source heavy metal ion adsorbent comprises the following steps: taking main stem tobacco stalk as a raw material, and performing the steps of specific surface area enlarging treatment, immersion treatment with an acid solution, and solid-liquid separating in order to obtain the tobacco source heavy metal ion adsorbent. The tobacco source heavy metal ion adsorbent takes the main stem tobacco stalk as the raw material, and is obtained by the steps of specific surface area enlarging treatment, immersion treatment with the acid solution, and solid-liquid separating in order; the tobacco stalk and tobacco leaf are homologous, the composition of the tobacco lead and that of the tobacco leaf are basically same, a non-tobacco component cannot be introduced into the tobacco extract, at the same time, the tobacco stalk has a lot of metal ion latent adsorption sites, which can creates conditions for adsorption of the heavy metal ion through modification treatment, and the adsorption test proves that the adsorbent presents good absorption effect for heavy metal ions in the tobacco extract.