Measuring　chlorophyll　fluorescence　is　a　direct　and　non-destructive　way　to　monitor　vegetation.　In　this　paper,　the　fluorescence　retrieval　methods　from　multiple　scales,　ranging　from　near　the　ground　to　the　use　of　space-borne　sensors,　are　analyzed　and　summarized　in　detail.　At　the　leaf-scale,　the　chlorophyll　fluorescence　is　measured　using　active　and　passive　technology.　Active　remote　sensing　technology　uses　a　fluorimeter　to　measure　the　chlorophyll　fluorescence,　and　passive　remote　sensing　technology　mainly　depends　on　the　sun-induced　chlorophyll　fluorescence　filling　in　the　Fraunhofer　lines　or　oxygen　absorptions　bands.　Based　on　these　retrieval　principles,　many　retrieval　methods　have　been　developed,　including　the　radiance-based　methods　and　the　reflectance-based　methods　near　the　ground,　as　well　as　physically　and　statistically-based　methods　that　make　use　of　satellite　data.　The　advantages　and　disadvantages　of　different　approaches　for　sun-induced　chlorophyll　fluorescence　retrieval　are　compared　and　the　key　issues　of　the　current　sun-induced　chlorophyll　fluorescence　retrieval　algorithms　are　discussed.　Finally,　conclusions　and　key　problems　are　proposed　for　the　future　research.