The magnetic properties and magnetoresistance effect of YMn6Sn6-x Crx (x = 0 - 0.8) compounds have beenexperimentally studied by magnetic properties and resistivity measurements in the applied field range 0 - 5 T.The compound (x = 0.8) displays a ferromagnetic behaviour, while the compounds (x = 0 - 0.4) display anantiferromagnetic behaviour in the whole ordering temperature range. The compounds (x = 0.5, 0.6) experienceda transition from an antiferromagnetic state to a ferromagnetic state with increasing temperature. The compoundwith x = 0.8 is rapidly saturated in the lower magnetic field with saturation magnetization of 35.92emu/g. Thecompounds (x = 0 - 0.6) display a field-induced metamagnetic transition, and the threshold fields decrease withincreasing Cr content. The cell-volume V of compounds (x = 0 - 0.8) increases, and the ordering temperaturedecreases with the increasing Cr content. A large magnetoresistance effect was observed for the compounds(x = 0.4, 0.5), and the maximum absolute value at 5K are 32% and 24% under 5T for x = 0.4 and x = 0.5,respectively.