  The influence of medium correction from an isospin dependent nucleon nucleon
cross section on the fragmentation and nucleon emission in the intermediate
energy heavy ion collisions was studied by using an isospin dependent quantum
molecular dynamical model (IQMD). We found that the medium correction enhances
the dependence of multiplicity of intermediate mass fragment $N_{imf}$ and the
number of nucleon emission $N_{n}$ on the isospin effect of the nucleon nucleon
cross section,while the momentum dependent interaction (MDI) produces also an
important role for enhancing the influence of the medium correction on the
isospin dependence of two-body collision in the fragmentation and nucleon
emission processes. After considering the medium correction and the role of
momentum dependent interaction the increase for the dependence of $N_{imf}$ and
$N_{n}$ on the isospin effect of two-body collision is favorable to learn the
information about the isospin dependent nucleon nucleon cross section
