The electroless deposition of Ni_ 68 -Fe_ 10.5 -P_ 21.5 alloy has been investigated. The crystallization behavior of the deposit was comparatively studied by using differential scanning calorimetry and X-ray diffractometry. The deposit transforms into a square Ni_ 3 P phase at 380.0 ℃, then changes into a cubic FeNi_ 3 phase at 490.0 ℃. The microhardness, the size of the formed grains and the magnetic performance of the deposit increase with the increase of the heat treatment temperature below 500 ℃, then they decrease after this temperature. The effect of heat treatment time at 500 ℃ on the surface micromorphology, the structure and the magnetic performance of the deposit were also studied. The results show that with the increase of heat treatment time, the extent of crystallization of the deposit increases and the size of the formed grains becomes uniform. The results also show that the magnetic performance of the deposit under heat treatment for 40 min is maximal and then decreases with the increase of heat treatment time. The property change of the deposit is related to the crystal structure and the size of the formed grains of the deposit. The electroless deposition of Ni 68 -Fe 10.5 -P 21.5 alloy has been investigated. The crystallization behavior of the deposit was comparatively studied by using differential scanning calorimetry and X-ray diffractometry. The deposit transforms into a square Ni_3P phase at 380.0 ° C , then changes into a cubic FeNi_3 phase at 490.0 ° C. The microhardness, the size of the formed grains and the magnetic performance of the deposit increase with the increase of the heat treatment temperature below 500 ° C., then they decrease after this temperature. The effect of heat treatment time at 500 ° C on the surface micromorphology, the structure and the magnetic performance of the deposit were also studied. The results show that with the increase of heat treatment time, the extent of crystallization of the deposit increases and the size of the results also show that the magnetic performance of the deposit under heat treatment for 40 min is maximal and then de creases with the increase of heat treatment time. The property change of the deposit is related to the crystal structure and the size of the formed grains of the deposit.