Abstract: The research of the sub-millimeter wave are being explored and developed.They have the important applications in military and civil areas.In this paper,a new method for objective with the passive sub-millimeter wave seeker system was given.The sub-millimeter wave electromagnetic radiometric pattern of the objective were discussed and the new generally solution was introduced.The detection distance of the passive sub-millimeter wave radiometer was given.And the influence of clouds（fog） attenuation,the temperature,and moisture for the detection distance were analyzed.