Abstract: Three materials including raw and water-washed ice straw, and microcrystalline cellulose with 5%KCl loaded were pyrolysed in the fixed bed reactor to investigate the transfer of potassium in four forms. The results indicate that the release of potassium changes little with pyrolysis temperature below 700 ℃, and the release of potassium dramatically increases with pyrolysis temperature above 700 ℃. During the rice straw pyrolysis, the transfer of four forms of potassium takes place, in which the water soluble and the potassium in residue decrease. It is confirmed that the potassium combined with carbon can be partly changed to water soluble, and the water soluble and organically bound potassium can exchange each other during pyrolysis.