Abstract: To improve the quality of tar, and reduce the heavy fraction (whose boiling points are greater than 360 ℃) in the tar, the lignite fast pyrolysis process using olivine and Co-impregnated olivine (Co/olivine) as the solid heat carrier was investigated in a fixed bed reactor over the temperature range 450~600 ℃. The effects of olivine and Co/olivine on the product yield, gas composition and tar fraction were examined. The results show that Co/olivine leads to a decrease in heavy oil fraction content, but an increase in tar yield. Co/olivine makes an increase in tar yield by 19.2% compared to the silica sand, while a decrease in heavy oil fraction content by 17.0% compared to the olivine at 550 ℃. The yield of light oil can reach up to 5.1%, however, the content of light oil, phenol oil and naphthalene oil increases by 19.6%, 17% and 15.2%, respectively. Meanwhile, the content of H₂ and CH₄ in gaseous product is obviously decreased.