The(Ni79Fe21)1-xNbx(5nm)/(Ni79Fe21) (20nm)/Ta(3nm) films are prepared with the (Ni79Fe21)1-xNbx seed layers. The grain size, hyste resis loops and surface roughness of samples are measured and the variations of hysteresis loops with the Nb atomic concentration in the seed layers are analyze d. The results show the microstructure of the permalloy films grown on the seed layers is improved. The coercivity and the (B·H)m in the hysteresis loop is minimal at x=23%.　The influence of seed layers on the hysteresis loops is partly duc to the different excitation energy of different seed layers, which result in different roughness of the surface of the seed layers film, hence the different microstructure of the permalloy films.