NOVELTY - Composite pore-forming agent is obtained by mixing spherical pore-forming agent and fibrous pore-forming agent in a mass ratio of 1-60:1-20.    USE - The composite pore-forming agent is useful for manufacturing batteries.    ADVANTAGE - The composite pore-forming agent can be prepared simply, and porosity of anode substrate is controlled easily. The anode supported flat plate type SOFC has excellent electrochemical performance and flexural strength.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for preparing flat-plate type solid oxide fuel cells (SOFC) using composite pore-forming agent, which involves (a) uniformly mixing nickel oxide and electrolyte powder, where total mass of anode initial powder is 40-70% of nickel oxide, (b) weighing spherical pore-forming agent and fibrous pore-forming agent, adding dispersant and water to spherical pore-forming agent, placing the mixture in ultrasonic oscillator for 0.5-2 hours, adding aluminum nitrate solution to fibrous pore-forming agent, placing the mixture in ultrasonic oscillator for 1-3 hours, centrifuging both pore-forming agent suspensions, uniformly stirring the suspension, and drying the suspension in an oven at 90 degrees C, (c) uniformly mixing anode initial powder and dried pore-forming suspension in a mass ratio of 100:5-30 with water as solvent, adding dispersant, binder and plasticizer to the mixture to obtain slurry, where the mass of dispersant is 0.8-1.5%, binder is 8-12%, water is 25-70% and plasticizer is 2-5%, (d) ball milling and mixing slurry, degassing the slurry and casting the slurry to obtain anode blank, (e) mixing yttria stabilized zirconia powder, dispersing agent, caking agent, water and plasticizer to obtain slurry, ball milling the slurry, degassing the slurry, allowing the slurry to flow to obtain electrolytic film, (f) hot-pressing electrolytic film and anode blank film to obtain half cell, and (g) discharge sintering the obtained half cell using plastic.