Dynamics of protein-like chains arc investigated by using Monte Carlo simulation method based on the modified ofientation．dependent monomer-monomer interactions model(ODI)．The diffusion coefficients for different chain length are calculated,and some comparisons with self-avoiding chains are also made．There exists a relationship between the diffusion coefficient D and chain length N for both protein—like chains and SAW chains．i．e D—N -a。．Here the valtie of αfor SAW chains is 1．02．however．the value of αfor protein-like chains iS 4．75,which iS 4～5 times larger than that of SAW chains．Therefore,dynamics of protein-like chains is different from SAW chains completely．These investigations may provide some insights into dynamics of proteins．