This work, concentrated on the effect of nuclear equation of state on the elliptic flow ( 2 v ) in heavy ion collision by using quantum molecular dynamics model (QMD). The elliptic flow of proton in 197 Au+ 197 Au collision at incident energy 0.25A GeV and impact parameter from 0 to 0.25 and from 0.25 to 0.45 within the quantum molecular dynamics model was studied. The theoretical calculations were performed with the nuclear equation of state (soft and hard EoS). The elliptic flow of proton as

more »

... function of the mid-rapidity ( 0 y ) was computed and compared with those from experiments. The calculated results show thet the behaviour of matter at high density and high temperature are described by a soft EoS. With the theoretical result, the elliptic flow of proton as a function of ( 0 y ) is consistent with the experimental FOPI data.