The secondary structure of adsorbed protein-like chain was investigated by using Monte Carlo simulation method based on the modified orientation-dependent monomer-monomer interaction model (ODI).The number of secondary structure such as α-helics

β-sheets and contacts are all calculated for different adsorbed energy and different chain length.When adsorbed energy εa2εh

the secondary structure of protein-like chains is nearly not changed.The chain is like a globe.While 2εhεa4εh

the number of α-helixs

β-sheets and contacts is reduced quickly.However

when εa4εh

secondary stucture is almost keeping again.The chain is flat because most residues are adsorbed on the surface.The reduced number of α-helixs is 90% of that without adsorption.However

the reduced number of β-sheets is 45%

and that of contacts is 35%.That is to say the effect of adsorbed energy on α-helix is the most

while effect on contact is the least.On the other hand

the fluctuations of the number of α-helix

β-sheets and contacts δNh

δNb are not changed at εa2εh.A peak is shown at εa=3εh

which is the transition point of secondary structure.Phase behavior of secondary structure is found with adsorbed energy changing.The fluctuation of the number of contact δNc and adsorbed residues δNa has the maximum at εa=3.75εh.