Abstract: Evaporation duct is a prevailing weather phenomenon that occurs on the sea, which is also the most important factor of anomalous propagation of electromagnetic wave. It influences the application of radar, correspondence and electronic equipment seriously. But there are some problems in the evaporation duct diagnosis model. For example, the diagnostic precision of many empirical functions summarized in land trials, is not validated in oceanic environment; the practicability of Monin-Obukhov Similarity Theory (MOST) in very low wind speed is limited; the seawater salinity has influences on water vapor press. TOGA COA RE flux algorithm supplies so me conditions for the precise diagnosis of Oceanic evaporation duct. Utilizing COARE 3.0 flux algorithm by Fairall and "gustiness" by Godfrey et al, the traditional MOST is appropriate to low wind speed condition, and evaporation duct model is established based on the flux algorithm (called Flux Evaporation Duct Model) combined with the precise atmospheric refractive index formula. Using the tower actual observation data in Ping tan Island during May, the Flux Evaporation Duct Model is compared with US Navy's Paulus-Jeske Model on evaporation duct height (EDH) and the profile of modified refractivity M. Gene rally speaking, the EDH calculated by the Flux Evaporation Duct Model is close to the actual data, superior to Paulus-Jeske Model obviously.But the two models' precision in the unstable cases is better than the stable cases. M-profiles computed by the Flux Model tally with the iron tower fitting results, the profile curvature computed by PJ Model is better, but there is obvious deviation for M value in the low altitude. In the comparison, it's found the EDH diagnosis accuracy does not mean the M profiles tally with the actual situation. Finally, using the marine radar sounding trial data in 2002, it's further verified the result that the Flux Model is able to provide good duct environment parameters for marine electro magnetic propagation computation and increase the precision of the radar sounding performance.