This paper extends the result of Hakan Andreasson. It's proved that the Cau
chy problem for the relativistic Boltzmann equation in a periodic box has a
global mild solution if the assumptions of the scattering cross section ar
e weaker than those given by Dudynski and Ekiel-Jezewska and include some h
ard relativistic interactions,and if the initial distribution function sati
sfies the conditions that it's periodic in the spacial space and that its m
ass,energy and. entropy are finite in the periodic box.