For the purpose of developing a composite micro sensor for bio-magnetic field, fabrication of high permeability ferromagnetic thin film by electroplating is needed. In this study, experimental investigations on the nanocrystalline size of electroplated NiFe in relation to the magnetic permeability of the plated layer are conducted. The plating methods include conventional DC plating, pulse plating, and addition of saccharin in conventional DC plating and pulse plating. The plating tests are made on 60mum diameter copper wires. The wires are plated in a standard set of procedure to ensure that the composition of the plated layer matches that of the Permalloy (Ni79Fe21). The permeability of the plated material is measured by measuring the magneto-impedance of the plated wire in variation with an external magnetic field, using a precision impedance analyzer. The nanocrystalline size of the plated NiFe is measured using a XRD machine. The results show that the permeability of the plated NiFe increases with the reduction of crystalline grain size. In conventional DC plating, the FCC of the plated layer beta-Ni (Fe) crystals are in the size of 16-19 nm. It is found that the wire, which has the highest impedance ratio, is the one from pulse plating with 6 g/l of saccharin in the electrolyte solution.