Test on the electrochemical mechanism of nickel depositing in ammonium bath with computer aided electrochemical workstation, the experiments were made on effect to nickel deposition by concentration of nickel sulfate & ammonium chloride and plating bath temperature & pH value. The results indicated that the cathodic polarization of matrix depositing increased by the addition of ammonium chloride with higher pH and lower temperature. This was beneficial for the refinement of nickel crystal and the electrode process was not affected by adding ammonium chloride. Indoor drilling tests were used to the selected bath formula by the electrochemical experiments. Bit of φ41/27mm was plated with the formula of 280g/L nickel sulfate, 19g/L ammonium chloride, 35g/L boric acid and 0.1g/L sodium dodecyl sulfate at pH value of 5.2, cathodic current density of 3.6A/dm2 and temperature of 45℃±1℃, the average penetration rate was 1.94m/h and wearing rate 0.092mm/m while drilling in sericitization quartz plagioclase porphyrite of drillability grade Ⅷ; the service life was similar to the conventional nickelcobalt electroplated bit, but the penetration rate was 0.18m/h higher.