A new method,named curvature compansation milling,is proposed to increase F/ of refractiave microlenses array (MLA).It is described as follows: in order to decrease curvature of MLA fabricated by the conventional method of photolithography/melting/ion beam milling,several new layers of photoresist are coated on MLA,then heated and consolidated,at last milled again.Scanning electron microscope (SEM) shows that microlens is gently spherical,and surface stylus measurement shows that F/ number and F′/ number of MLA,fabricated by the new method,is promoted to 31.62 and 35.88,respectively,compared with 1.00 and 4.00,hardly obtained by use of conventional way.And the filling factor is promoted from 64.3% to 78.5%.Using the new method,point spread funtions of MLAs are more ideal,and their image quality is improved.