The effects of interactions between RS and HDPE on the evolution of volatile species and their distributions during co-pyrolysis of rice straw (RS) and high density polyethylene (HDPE) was investigated by thermogravimetric analyzer coupled with fourier transform infrared spectroscopy and mass spectrometry technology (TG-FTIR-MS). It can be found that the pyrolysis process of RS and HDPE blends was characterized by two stages. The first stage primarily consisted of the decomposition of RS. The second stage was dominant by the degradation of HDPE. The interactions between RS and HDPE were obvious in the temperature range of 435-520 degrees C. The existence of HDPE delayed the decomposition of RS in the first step, while in the second step, the existence of RS delayed the degradation of HDPE. The primary gaseous products for the blends arose from the overlap of the decomposition products from the individual RS and HDPE. However, no new substance can be observed in the blends compared to the decomposition of individual RS and HDPE. The primary gaseous products were Hy, H2O, CO2, CO, aldehydes (C2H4O), alcohols (C2H5OH), carboxyls (CH3COOH) and hydrocarbons (CH4, C2H2, C2H4, C2H6, C3H6, C3H8). The addition of HDPE in the blends could decrease the amount of the oxygen-containing compounds, and improve the yield of Hy and hydrocarbons. The effects of the interaction between RS and HDPE on the evolving of volatile species were affected by the percentage of RS in the blends. (C) 2017 Elsevier Ltd. All rights reserved.