Study　of　technological　knowledge　diffusion　can　provide　a　basis　for　R&D　planners　to　invest　new　R&D　projects　with　a　proper　direction.　In　this　paper,　we　introduce　a　modified　method　to　analyze　the　diffusion　degree　of　technological　knowledge　among　different　technological　fields　using　patent　data　at　the　technology　patent　class　level.　This　method　first　generates　a　patent　citation　network　related　to　a　specific　research　area　and　then　establishes　a　technological　field　diffusion　matrix　according　to　the　concordance　between　the　patent　document　and　the　corresponding　patent　class.　After　that　indicators　are　set　up　to　measure　the　diffusion　degree　of　technological　field　from　two　aspects　of　diffusion　depth　and　breadth　and　then　we　discern　the　diffusion　type　of　typical　fields.　Finally,　we　conduct　microfluidic　technology　as　a　case　study　to　prove　the　feasibility　of　the　method.　©　2017　World　Scientific　Publishing　Company.