A new outdoor simulation system on the basis of the electric heating cloth is developed to simulate infrared radiance of outdoor targets.The cloth is taken as an infrared radiant material and appended to a rectangle target filled with air.Then a temperature control system is used to control the surface temperature of the cloth according to the temperature setting and to implement the infrared radiance simulation of outdoor targets.There are two major contributions in the paper.Firstly, uneven distribution of temperature field of the cloth surface is considered and a long wave infrared thermal imager is used as a link of temperature control system.On the basis of many experiments, an expression is concluded on the relation of the temperature measurement results, the setting temperature of control system and the environmental temperature at an experimental scene.This expression can help for setting temperature of the cloth surface through temperature control system according to the giving infrared radiance of targets.Secondly, the influence of the environment at the experimental scene on the infrared radiance of the cloth surface is thought over.By two considerations above,the simulation precision of infrared radiance has been up to 2 ℃.The outdoor experimental results demonstrate that the system could simulate infrared radiance of outdoor targets in a certain range accurately.