NaCl and its mixed salt have many advantages as medium of solar energy phase change thermal storage at moderate and high temperature. But molten chloride has sharp corrosive action on metal thermal storage vessel. The corrosion behavior of three kinds of Ni-10 wt. % Fe based sample (1#, 2# and 3#) in 850℃ molten NaCl was studied. The content of Al in 1#, 2# and 3# sample is 0.0 wt. %、5.0 wt. % and 10.0 wt. %, respectively. The components of NaCl after corroding and corrosion products on samples surface were analyzed. Elements change trend and corrosion characteristic on cross section of the three samples were contrasted. Corrosion mechanisms were discussed finally. Results show that the kinetics curves of the three kinds of sample obey liner rule. The average mass loss rate reduce when Al is added in sample. The rate of 2# and 3# is only 12% and 20% of 1#, respectively. There are two reasons for the value reduction: first, Al will be oxidized prior to oxidization of Fe or Ni, and the atomic mass of Al is small. Second, Al2O3 is very stable at high temperature as corrosion products. However, when the content of Al is very high (for example 10 wt. % in here) in Ni-10 wt. % Fe based alloy, Al oxidized on sample surface provides convenient condition for Al atom transmission from sample matrix to surface.Al2O3 film becomes thick and exfoliates easily. The exfoliation led to the average mass loss rate increase in turn. The study establishes foundation for new corrosion resistance alloy research in molten salt.