Ghrelin is a unique peptide hormone that releases growth factor and it stimulates appetite. It comes from pre pro-ghrelin by the post translational modification process and its innate functions are known as food up-take and the growth hormone regulation. Therefore, the structural information of ghrelin precursor is of importance in understanding it function. From our results, we found that the solution structure of ghrelin is mostly random coil conformation at neutral pH value and the structural population changes with pH environments. Data from circular dichroism in different TFE concentrations revealed that the secondary structure changes from random coil to a-helix and the isodichroic point is observed at 202nm, implying that two equilibrium states exist between random coil and helical structure.