The crystal structure of the ternary compound Y(Mn1-xCox)12 With x = 0.3, 0.5 and 0.6 is body-centered tetragonal of ThMn12 type. The space group is I4/mmm, z= 2. Powder neutron diffraction studies on this system has been performed to determine the possible ordering of the Co and Mn atoms on 3 nonequivalent crystallo-graphic sites 8i, 8j and 8f. The structure analyses at room temperature shows that the Co atoms tend to occupy the 8f sites primarily and then the 8j sites. They avoid the 8i sites when x is lower than 0.67. The experimental result is discussed and an inference is drawn.