The construction of fire zone modeling involves two crucial steps:: establishing mathematical model for every phenomenon existing in course of a fire
and calculating some fire parameters such as compartment pressure
temperature
and height of smoke layer by solving equations.The latter is the core of zone simulating programming and fire risk assessment
especially in solving pressure equations.The solution of pressures is the prerequisite for solving other parameters.This paper presents the method of solving pressure equations and especially describes the details of the method for solving pressure equations for single compartment fire.Finally