Breccia develops widely in the middle and lower part of reservoir in Longlake oil sand, Canada. Based on characteristics of permeability and extension of breccia in the target area, numerical simulation method was used to study the impact of vertical permeability of breccia and its extension along the wellbore on well pattern and development index. In this process, three different conditions were considered, including injector drilled in breccia, producer drilled in breccia and breccia between injector and producer. The results show that with the same permeability and extension, the impact of breccia drilled by injector on the expansion of steam chamber was smaller than that drilled by producer or between injector and producer. If the breccia was drilled into by well or it was located between injector and producer, the subsequent trajectory should be adjusted if continuous length of breccia was larger than 50m. For breccia with different extension, the relationship chart between vertical permeability of breccia and development index could provide a guiding role for the design of SAGD well pattern.