Abstract: This paper briefly presented development history of upconversion materials and four mechanisms leading to upconversion Luminescence.Upconversion laser and luminescence systems were reviewed and the factors affecting luminescence including host materials,sensitized luminescence and single and dual wavelength pump were discussed.

Key words: This paper briefly presented development history of upconversion materials and four mechanisms leading to upconversion Luminescence.Upconversion laser and luminescence systems were reviewed and the factors affecting luminescence including host materials,sensitized luminescence and single and dual wavelength pump were discussed.