MnZn soft ferrite materials with NiO-CoO dopant are prepared by conventional oxide technique.The influences of CoO and NiO addition on the microstructure and magnetic properties of low-loss and high Bs MnZn ferrites are investigated. The present results show that MnZn soft ferrite materials with CoO addition of 0.1wt% and NiO addition of 1.28wt% possess both homogeneous grains and high saturation magnetic flux density. The lowest loss point is located at 100°C. The valley point of power loss shifts to higher temperature with increasing of NiO dopant. The power losses decrease and sintering density increases with increase of CoO addition. The sintered MnZn ferrite materials based upon a specific sinter curve possesss excellent comprehensive properties: μi=2198 , Pcv=319 kw/m3 , Bs=540mT (T=25°C), Bs=451mT (T=100°C).