The invention provides a production method for smelting F55 dual-phase steel in an intermediate frequency furnace. The production method comprises the following steps that S1, molten steel is prepared in the intermediate frequency furnace according to the following ingredients in percentage by mass: less than or equal to 0.03% of C, less than or equal to 1.00% of Si, less than or equal to 1.00% of Mn, less than or equal to 0.02% of P, less than or equal to 0.015% of S, 24.0%-26.0% of Cr, 6.0%-8.0% of Ni, 3.0%-4.0% of Mo, 0.2%-0.3% of N and the balance of Fe; S2, abottom slag accounting for 2% of the weight of the molten steel is added into the intermediate frequency furnace, and melting is conducted; S3, after melting down, a Si-Ca wire is added for deoxidation; S4, slagging off is conducted after adding Si-Ca wires for 10 minutes, and high-aluminum refractory brick fragments and CaF2 are added to make new slag; S5, a deoxidizing agent is added into the slag layer in batches for first diffusion deoxidation; S6, components in front of the furnace are sampled and analyzed, FeCrNi alloy and alloy elements of Si, Mn, Mo and N are supplemented, and then diffusion deoxidation for the second time is conducted; and S7, the slag amount is adjusted, and tapping is conducted after white slag is kept for 15 minutes. Compared with the prior art, the oxygen content and the inclusion content in the intermediat requency smelting duplex stainless steel are reduced through reasonable intermediate frequency smelting burdening, deoxidation and slagging processes.