diff --git a/fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java b/fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java
index f8d8a1fda2..7879f5ed86 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java
@@ -56,6 +56,7 @@ import org.apache.doris.analysis.ReplaceTableClause;
 import org.apache.doris.analysis.SelectStmt;
 import org.apache.doris.analysis.SetOperationStmt;
 import org.apache.doris.analysis.SetStmt;
+import org.apache.doris.analysis.SetType;
 import org.apache.doris.analysis.SetVar;
 import org.apache.doris.analysis.SetVar.SetVarType;
 import org.apache.doris.analysis.ShowStmt;
@@ -954,6 +955,19 @@ public class StmtExecutor {
             for (SetVar var : setStmt.getSetVars()) {
                 VariableMgr.setVarForNonMasterFE(context.getSessionVariable(), var);
             }
+        } else if (parsedStmt instanceof UnsetVariableStmt) {
+            UnsetVariableStmt unsetStmt = (UnsetVariableStmt) parsedStmt;
+            if (unsetStmt.isApplyToAll()) {
+                VariableMgr.setAllVarsToDefaultValue(context.getSessionVariable(), SetType.SESSION);
+            } else {
+                String defaultValue = VariableMgr.getDefaultValue(unsetStmt.getVariable());
+                if (defaultValue == null) {
+                    ErrorReport.reportDdlException(ErrorCode.ERR_UNKNOWN_SYSTEM_VARIABLE, unsetStmt.getVariable());
+                }
+                SetVar var = new SetVar(SetType.SESSION, unsetStmt.getVariable(),
+                        new StringLiteral(defaultValue), SetVarType.SET_SESSION_VAR);
+                VariableMgr.setVar(context.getSessionVariable(), var);
+            }
         }
     }
 
diff --git a/fe/fe-core/src/main/java/org/apache/doris/qe/VariableMgr.java b/fe/fe-core/src/main/java/org/apache/doris/qe/VariableMgr.java
index 13fe89acbb..93c842f0bf 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/qe/VariableMgr.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/qe/VariableMgr.java
@@ -715,21 +715,15 @@ public class VariableMgr {
             throws DdlException {
         for (Map.Entry<String, VarContext> entry : ctxByDisplayVarName.entrySet()) {
             VarContext varCtx = entry.getValue();
-
-            SetType newSetType = null;
-            // some variables are GLOBAL only or SESSION only
-            if ((varCtx.getFlag() & GLOBAL) != 0) {
-                newSetType = SetType.GLOBAL;
-            } else if ((varCtx.getFlag() & SESSION_ONLY) != 0) {
-                newSetType = SetType.SESSION;
-            }
-
-            SetVar setVar = new SetVar(newSetType != null ? newSetType : setType, entry.getKey(),
+            SetVar setVar = new SetVar(setType, entry.getKey(),
                     new StringLiteral(varCtx.defaultValue), SetVarType.SET_SESSION_VAR);
-            //skip read only variables
-            if ((varCtx.getFlag() & READ_ONLY) == 0) {
-                setVar(sessionVariable, setVar);
+            try {
+                checkUpdate(setVar, varCtx.getFlag());
+            } catch (DdlException e) {
+                LOG.debug("no need to set var for non master fe: {}", setVar.getVariable(), e);
+                continue;
             }
+            setVarInternal(sessionVariable, setVar, varCtx);
         }
     }