The invention relates to a waste circuit board harmless treatment method, which comprises: (1) crushing a waste circuit board; (2) conveying the crushed waste circuit board into a vibration sieve, and screening; (3) conveying the broken material into a pyrolysis furnace, and cracking; (4) cooling the mixed metal residue, conveying into a drum sieve, and screening to obtain a material on the sieve and a material under the sieve; and (5) burning the waste gas generated in the step (3), purifying, removing the dust, and carrying out standard discharging. According to the present invention, the small particle material is selected by breaking and screening the circuit board, and then is conveyed into the pyrolysis furnace and cracked, the recyclable metal components of the waste circuit board are obtained through the decomposing, the metals are separated through cooling and screening to obtain the metal recovery product, and the waste gas during the cracking process is subjected to burning, purifying and dust removing so as to achieve the standard discharging; and with the application of the method to treat the waste circuit board, the metal recovery rate is high, the separation effect is god, and the advantages of environmental protection and no pollution are provided.