Electroforming process in precision mold with large area microstr uctures is studied. Effects of micro chemical etching， mask thickness an d secondary auxiliary cathode on large area microstructures of precision mold fabricated b y the electroforming process are discussed. The results show that， it can be strengthened by micro chemical etching step for further removing the developing adhesive residue and improving the coating adhesion between the micr ostructure and the mold substrate. The microstructures with best sidewall angle can be obtained in the conditions that the exposure time is 100 s， the exposure ener gy is 750—810 mJ/cm2， the mask thickness is 130—160 μm， and the precisi on dies is with the line width of 100 μm side. Furthermore， the three electrode electroform ing system with a potential secondary auxiliary cathode can improve the uniformi ty of the electrodeposition layer.