diff --git a/debian/copy_installer.sh b/debian/copy_installer.sh
index 8997e87d0..556899e9a 100755
--- a/debian/copy_installer.sh
+++ b/debian/copy_installer.sh
@@ -1,8 +1,14 @@
 if [[ x"$1" =~ x"v2" ]]
 then
-   echo "Copy python-saithriftv2.install as python-saithrift.install"
-   cp ./debian/installerFiles/python-saithriftv2.install ./debian/python-saithrift.install
+   echo "Copy python3-saithrift.install as python-saithrift.install"
+   cp ./debian/installerFiles/python3-saithrift.install ./debian/python-saithrift.install
 else
-   echo "Copy python-saithriftv1.install as python-saithrift.install"
-   cp ./debian/installerFiles/python-saithriftv1.install ./debian/python-saithrift.install
+   if [ $(lsb_release -sr) -ge 11 ]
+   then
+      echo "Copy python3-saithrift.install as python-saithrift.install after Ver.11 releases"
+      cp ./debian/installerFiles/python3-saithrift.install ./debian/python-saithrift.install
+   else
+      echo "Copy python2.7-saithrift.install as python-saithrift.install"
+      cp ./debian/installerFiles/python2.7-saithrift.install ./debian/python-saithrift.install
+   fi   
 fi
diff --git a/debian/installerFiles/python-saithriftv1-bullseye.install b/debian/installerFiles/python-saithriftv1-bullseye.install
new file mode 100644
index 000000000..5745e926a
--- /dev/null
+++ b/debian/installerFiles/python-saithriftv1-bullseye.install
@@ -0,0 +1,2 @@
+#compatiable with bullseye python 3.9 environment
+debian/usr/local/lib/python3.9/site-packages/* /usr/lib/python3/dist-packages/
diff --git a/debian/installerFiles/python-saithriftv2.install b/debian/installerFiles/python-saithriftv2.install
deleted file mode 100644
index e3d2e8c13..000000000
--- a/debian/installerFiles/python-saithriftv2.install
+++ /dev/null
@@ -1 +0,0 @@
-debian/usr/local/lib/python3*/site-packages/* /usr/lib/python3/dist-packages/
diff --git a/debian/installerFiles/python-saithriftv1.install b/debian/installerFiles/python2.7-saithrift.install
similarity index 100%
rename from debian/installerFiles/python-saithriftv1.install
rename to debian/installerFiles/python2.7-saithrift.install
diff --git a/debian/installerFiles/python3-saithrift.install b/debian/installerFiles/python3-saithrift.install
new file mode 100644
index 000000000..38be43db2
--- /dev/null
+++ b/debian/installerFiles/python3-saithrift.install
@@ -0,0 +1,2 @@
+#compatiable with bullseye python 3.9 environment and saithriftv2 build with python3
+debian/usr/local/lib/python3*/site-packages/* /usr/lib/python3/dist-packages/