Abstract: The kinetics simulation of KrF laser has been done for the design of 100J KrF laser system by zero-dimensional calculations. Its results are in agree ment with experimental results of our laboratory and Sandia National Laboratory (U.S.A.). It is very useful for improvement of the intrinsic laser efficiency of the KrF laser device, design of the laser cell and some requirements of the electron beam for the laser device. A simple and practical model of calculation is given.