2-Methylfuran (MF), an environmental-friendly biofuel, has drawn extensive attention from fuel researchers. In this study, the particulate matter (PM) and unregulated emissions of diesel engine were investigated. All experiments were performed in a direct injection compression ignition (DICI) engine fueled with diesel-MF blends (10%, 20% and 30% mass fractions of MF were blended with diesel). The test conditions were a constant speed of 1800 rpm and load from 0.13 to 1.13 MPa brake mean effective pressure (BMEP). Among the tested fuels, the emissions of 1,3-butadiene, benzene and acetaldehyde are all decreased with the increase of engine load except benzene of M30 at 1.13 load. In addition, the diesel-MF blends promote acetaldehyde emissions, but reduce benzene and 1,3-butadiene emissions. At the engine load of 0.38 MPa BMEP, with the increase of MF fraction in blends, more particle numbers for both nucleation mode and accumulation mode are yielded than pure diesel. At 0.88 and 1.13 MPa BMEP, with the increment of MF ratio in blend fuels, the particle numbers rise at small diameter of particle (Dp) (5-10 nm) compared to pure diesel, but decline at large diameter of particle (Dp) (10-250 nm). The increment of MF blending ratio increases the particulate number concentration. Moreover, with the rise of MF mass fraction in the mixtures, the particulate mass concentration decreases gradually at above 0.63 MPa BMEP. However, particulate mass concentration of M30 is the highest at lower loads. (C) 2017 Elsevier Ltd. All rights reserved.