he rare-earth magnetic alloys of YTi(Fe(1-x)Cox)(11) system (x=0.0, 0. 15, 0.25, and 0.5) have been prepared and the optimal reaction condition has been worked out by using the method of coprecipitation-reduction diffusion.By studing the crystal structure with XRD and testing the Curie temperature and magnetization on the VSM of model M 155, it is shown that all the YTi(Fe(1-x)Cox)(11) system alloys has the crystal structure of ThMn12 type,the lattice parameters decrease and the Curie temperature increases with the Co addition amount increasing, the reduced saturated magnetization has a maximum at x=0. 15.