Heat transfer in the thrust chamber is of great importance in the design of liquid propellant rocket engines. Regenerative cooling is an advanced method which can ensure not only the proper running but also higher performance of a rocket engine. The theoretical model is complicated, it relates to fluid dynamics, heat transfer, combustion, etc... In this paper, a regenerative cooling model is presented. Effects such as radiation, heat transfer to environment, variable thermal properties and coking are included in the model. This model can be applied to all kinds of liquid propellant rocket engines as well as similar constructions. The modularized computer code is completed in the work.