The　two　magnetic　measurement　methods　of　superconductors.　SQUID　method　and　Campbell　method,　are　introduced　briefly.　Superconducting　properties　of　MgB2　bulk　samples　are　prepared　by　the　high-pressure　powder　in　tube　(PIT)　sintering　method　The　two　measurement　methods　are　employed　to　measure　the　critical　current　density　of　the　sample.　The　J(c)-B　curves　of　the　MgB2　samples　are　obtained　with　each　method.　The　SQUID　method　can　be　used　to　measure　the　magnetic　strength　field　up　to　6　T　and　the　material　is　in　normal　state,　and　the　result　is　used　to　scale　F(b)　of　the　pinning　through　necessary　calculation　which　is　used　to　study　the　magnetic　characteristic　of　the　material.　The　critical　current　density　(J(c))　measured　by　the　SQUID　method　is　the　average　of　the　materials　different　parts.　J(c)　is　measured　and　estimated　by　the　Campbell＇s　method.　The　magnetic　field　is　only　to　0.4　T　while　the　frequency　of　the　AC　parts　magnetic　field　is　varied　from　37　Hz　to　797　Hz.　The　critical　current　density　obtained　by　Campbell＇s　method　is　smaller　than　that　obtained　by　the　SQUID　measurement,　which　is　due　to　the　existence　of　various　faults　and　the　decrease　of　the　electrical　connectivity.