Mn 1−x Zn x Fe 2 O 4 thin films with various Zn content were deposited on Si (100) substrate by alternately sputtering from two targets with the composition of MnFe 2 O 4 and ZnFe 2 O 4 , respectively. The as-deposited films are amorphous. After being annealed in the vacuum furnace with air pressure P Air =2×10 −1 Pa at suitable temperature, crystalline Mn–Zn ferrite films are obtained. The optimum annealing temperature is 550°C, at which a maximum of saturation magnetization and a minimum of coercivity are obtained. For Mn 1−x Zn x Fe 2 O 4 thin films, the saturation magnetization increases firstly then decreases and coercivity decreases monotonously with increasing Zn content. The Mn–Zn ferrite thin films with ZnFe 2 O 4 underlayer exhibit better magnetic properties than those deposited directly on Si substrates because ZnFe 2 O 4 underlayer not only can impede the diffusion between the substrate and magnetic layer, but also can decrease the strain caused by mismatch between the lattice constants of the substrate and thin films.