Abstract: In this paper, a double square metal pole waveguide filter was designed based on the mode matching method（MMM）. The square metal poles were replaced by cylindrical metal poles by using the empirical formula. After which, the conversion formula between traditional waveguide and substrate integrated waveguide （SIW） was adopted to obtain SIW filter. The use of double metal pole aims improves the out-off-band rejection for the filter. This type of filter has a simple structure, low cost and be easily fabricated. So it is very suitable for quantity production. HFSS simulation result of the designed fabric proved the precision of the mode matching method and the validity of the empirical formula.