This　paper　is　devoted　to　set　up　a　measuring　module　of　manufacturing　system　flexibility　with　fuzzy　set　theory　via　the　method　of　template　method.　Starting　with　the　analysis　on　the　interrelationship　between　input　and　output　of　the　manufacturing　system,　a　module　based　on　the　function　of　degree　of　membership　is　built　up.　Proofs　have　been　provided　to　identify　the　extremum　and　the　monotone　descent　property　of　the　module.　Method　of　defining　the　optimized　output　of　manufacturing　system　as　per　various　levels　of　its　flexibility　is　also　presented.　With　the　help　of　flexibility-output　surplus,　it　is　illustrated　that　any　pursuit　of　flexibility　is　based　on　increasing　costs　and　waste　of　manufacturing　capability.