The detection problem of dim signal is studied based on narrowband dual-polarization radar system. Firstly the probability density functions of different signals and a novel detection algorithm are presented through polarization and power accumulation in time .We also derive the analytical expression for the probability of false alarm and show that the new receiver can be made bounded constant false alarm rate (CFAR).Then a solution is showed through proving the same distributions between different coordinates of the statistics by which the radar detection performance can be simplified. Finally

we present simulation results

which show the radar detection performance can be obviously improved. It can be useful to anti-radar stealthy

early warning and space detection or other applications.