The invention discloses a method for preparing a flat-plate type metal-support solid oxide fuel cell. The method comprises the following steps of: firstly respectively preparing three layers of biscuits such as a porous metal support layer, a compact electrolyte layer and a porous cathode precursor layer, then superimposing from bottom to top in sequence for carrying out hot pressing, then carrying out high-temperature common sintering, using a surface active agent to carry out surface treatment on the porous metal support layer, finally immersing a salt solution of an active cathode material in the porous cathode precursor layer, and performing heat treatment, so as to obtain a cathode of the cell; and immersing a salt solution of an active anode material in the porous metal support layer, performing the heat treatment, so as to obtain an anode of the cell. The method has the advantages that the cost is low, the operability is strong, the batched and continuous production is convenient; and according to the prepared cell, the combination among all the layers is close, the thickness, the porosity and the like of all the function layers can be controlled, the cathode and the anode of the cell are prepared by immersion, the performance of the cell is high, the stability is good, the service life of an electric pile can be guaranteed, the cost of a system is reduced and the application prospect is very good.