Abstract: The microwave removing process of residual dimethyl sulfoxide （DMSO） from polyacrylonitrile （PAN） films was studied using X-ray diffraction， elemental analysis， and scanning electron microscopy. The effects of microwave power and processing time on the DMSO removal efficiency， microstructure， and mechanical properties of PAN films were analyzed. The experimental results indicated that the residual amount of DMSO in PAN continued to decrease with an increase in the microwave processing power and microwave processing time. The crystallinity of PAN film tended to decrease at first and then increased. Meanwhile， the grain size continued to increase， the micropore size of PAN film decreased significantly， the overall tensile strength increased， and the elongation at break decreased. After treated with 540 W microwave for 4 minutes， the tensile strength of the PAN film reached 21.36 MPa， which was 46.5 % higher than that of the initial film. The average pore size inside the PAN film decreased and the overall structure became denser.

Key words: polyacrylonitrile film, residual dimethyl sulfoxide, microwave, removal, microstructure