When the neutron radioactive capture cross section and the. inelastic scattering cross section ((n,γ), (n,n')) are measured, the neutron flux in the sample isn't equal everywhere due to neutron multiscattering and sel-fabsorption in the finite sample.In the early work, it's supposed that neutron f lux in the sample is equal everywhere in the data processing which brings some uncertainties to the experimental values of (n,γ) and (n,n') cross section.Although it has been tested and verified by experiments that these two kind of effects can be roughly compensated each other in the special geometric sample,in order to get more accurate results, it is necessary to calculate these effects,Present work is to calculate the correction factor for the fast neutron multiscattering and self-absorption in the sample with Monte Carlo simulation method. In the real mathematical processing with Monte Carlo, because geometric size of the sample is more small in general, the forcecollision method is used in the transport procedure.To treat the collision procedure, the weighting process for scattering is adopted.Both expectation estimation method and path-length estimation method are used to record the flux distribution. We calculated the correction factor for 14 MeV neutron multiscattering and self-absorption by ⁵⁶Fe.The results are in accord with experiment an-alyses.