In　this　work,　a　multiple　speech　source　separation　method　is　proposed　based　on　single　source　zone　detection　and　linearly　constrained　minimum　variance　(LCMV)　beamformer.　First,　the　＇single-source＇zones　where　only　one　source　is　dominant　over　the　others　are　detected　according　to　the　characteristic　of　B-format　microphone.　Second,　the　number　of　active　sources　and　their　corresponding　directions　of　arrival　(DOAs)　are　estimated　in　these　＇single-source＇zones.　Finally,　LCMV　beamformer　is　adopted　for　recovering　the　sources　separately　by　using　the　DOA　estimates.　The　objective　evaluation　shows　that　the　proposed　method　achieves　better　separation　quality　compared　to　some　existing　BSS　(blind　source　separation)　approaches.　©　2020　ACM.