It　is　known　that　the　active　layer　morphology　of　bulk　heterojunction　organic　solar　cells　has　significant　impact　on　the　performance　of　solar　cell　devices.　However,　the　widely　used　morphology　characterization　methods　such　as　transmission　electron　microscopy　(TEM),　atomic　force　microscopy　(AFM)　have　certain　limitations　in　the　characterization　of　organic　thin　film　materials.　By　using　the　huge　difference　of　the　refractive　index　of　the　different　materials　under　the　soft　X-ray,　resonant　soft　X-ray　scattering　(R-SoXS)　provides　highly　enhanced　contrast,　overcomes　the　drawbacks　such　as　low　contrast　between/among　different　organic　components　and　the　lack　of　3D　information,　which　is　important　to　obtain　the　phase　separation　information　in　the　active　layer　of　organic　solar　cells,　to　understand　the　microstructure,　and　to　establish　the　relationship　between　the　morphology　and　the　photoelectric　conversion　process.　This　article　provides　an　overview　of　the　effect　of　active　layer　morphology　on　the　performance　of　bulk　heterojunction　organic　solar　cells,　introduces　the　developing　process,　theoretical　background　and　the　analysis　method　of　resonant　soft　X-ray　scattering.　Based　on　these,　the　application　of　resonant　soft　X-ray　scattering　in　the　study　of　the　morphology　of　organic　solar　cells　is　reviewed.　The　application　prospects　of　R-SoXS　are　also　discussed.