This paper reports a simple and novel procedure for fabricating the mold insert of microlens arrays. In this paper, an L-g experimental matrix design based on the Taguchi method is constructed to optimize the replication quality of molded microlens arrays. The results of the statistical analysis indicate that the processing temperature is the principal parameter affecting the sag height of the molded microlens array. The 200 x 200 arrays of molded microlens, with a diameter of 150 mu m, a pitch of 200 mu m and a sag height of 31.51 mu m have been successfully fabricated. The average surface roughness of the Ni mold insert is 6.916 nm. The average surface roughness of the molded microlens array is 4.608 nm. The processing temperature is the most important factor for the radius of curvature of molded microlens.