In this paper, the effects on the microstructure and mechanical properties of twin-roll casting 6061 aluminum alloy plates with Mn addition were investigated. The microstructure of 6061 cast-rolled plates were analyzed by means of thermodynamic simulation and Optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The mechanical properties of 6061 cast-rolled plate with different Mn contents were tested using tensile tests. The results showed that, with the increase of Mn content of the 6061 cast-rolled plate, the iron-rich phase at the edge of 6061 cast-rolled plates gradually transformed from acicular β-Al5FeSi phase to granular α-Al12(FeMn)3Si phase, a large number of irregular blocks and a petal-like α-Al15（FeMn）3Si2 phase aggregated in the core（ω(Mn)=0.54 wt.%）; When ω(Mn)=0.36 wt.%, the mechanical properties of 6061 cast-rolled plate were the best. At this time, the tensile strength, yield strength and elongation of cast-rolled plates were 195.93 MPa, 170.36 MPa and 17.96%,