Abstract: Based on the experimental investigation of low pressure and low quality vapour water two phase flow density wave oscillation carried out at Institute of Nuclear Energy Technology of Tsinghua University, a homogeneous analysis model for the thermalhydraulic test loop of 200 MW heating reactor(HRTL 200) is presented. The analysis results of steady state and density wave oscillation show that the calculated mass flow rate is larger than experimental one, and the homogeneous model neglected the subcooled boiling region can not predict both of small and large subcooling stability boundaries in the narrow low quality unstable region, although it can predict that there are two density wave oscillation regions in low quality and high quality regions.