The invention provides a method for producing a double-surface thick copper flexible working board. The invention is characterized by comprising the steps of a first step, drilling; a second step, chemical treatment; a third step, copper deposition; a fourth step, electroplating; a fifth step, pattern transferring; a sixth step, acid etching; a seventh step, covering film pressure-overlying, wherein the seventh step comprises procedures of A, treating a copper surface by means of a copper surface coarsening solution for etching the copper surface to a coarse surface and forming a honeycomb-shaped surface, B, in performing covering film pressure-overlying, utilizing silicone rubber with hardness of 45+ / -5 DEG C and temperature resistance of 250 DEG C above and below the substrate as accessories for ensuring high pressure overlaying effect of the covering film, and C, at a press jointing temperature of 190-200 DEG C and a press jointing pressure of 10-15Kg / m<2>, performing press jointing for 2-4 minutes, thereby jointing the substrate with the covering film for obtaining the working board. Because the technical solution is used, the method for producing the double-surface thick copper flexible working board has advantages of simple process, low cost, high drilling quality, and electroplating uniformity. The method further prevents the problems of bubbles on the covering film, filling glue insufficiency, thermal shock and laying in a reflow soldering test.