An　accurate　measurement　method　of　the　polarized　light＇s　phase　retardation　based　on　the　crystal　wedge　is　introduced,　and　is　applied　to　measure　the　phase　retardation＇s　temperature　dependence　of　the　zero-　and　multiple-order　quartz　wave　plates.　The　measured　results　are　insensitive　to　the　power　fluctuation　of　the　light　source,　and　the　accuracy　of　the　phase　measurement　can　reach　0.05°.　Compared　to　the　traditional　phase　measurement,　there　is　no　adjustment　of　any　optical　components　during　the　crystal　wedge＇s　experiments,　the　on-line　phase　detection　can　be　realized.　This　method　can　be　used　at　the　phase　retardation　measurement　of　any　optical　components,　or　at　the　various　optical　wavelengths.