Abstract: The co-gasification of rice straw with PVC was carried out in a fixed bed reactor; the transformation of K, Na and Cl elements was investigated through X-ray diffraction (XRD) and thermodynamic calculation. The results indicated that the release of chlorine is related to the operation temperature and PVC proportion in the co-gasification of rice straw and PVC. The content of PVC in the blend plays an important role in the release of Cl, especially at 800~900 ℃; the amount of Cl released in gasification of the blend with 20% PVC (11.5% Cl) is increased by 16.5%, compared with that of pure rice straw at 900 ℃. Meanwhile, the increase of Cl content in the blend also prompts the release of K and Na. When the fraction of PVC is higher than 20% (> 11.5% Cl), the presence of Cl can restrain the release of K and Na at 850 ℃, which are retained in the ash as KCl and NaCl during the co-gasification of rice straw and PVC at 850 ℃; the content of which decreased with the increase of PVC countent in the blend.