Based on constructal theory and entransy theory, an experimental study on + shaped high conductivity channels in a square body is carried out. Heat conduction performance comparisons of the bodies based on different optimization objectives and different layouts of the high conductivity channels are performed. In the experiment, the materials of the square body and high conductivity channel are epoxy resin and brass, respectively; the brass channel is embedded in the square body. Two square heating boards, closed at the upper and lower sides of the square body, are used to uniformly heat itself. The internal heat generation of the square body is approximately simulated by this method. The square body is placed in a thermal insulation box to reduce the heat dissipation caused by heat convection. The heat generated by the heating boards is absorbed by the outside refrigerator device. A measurement window is set at the front side of the thermal insulation box. The temperature field of the square body is measured by the infrared thermal imager. The peak temperature, average temperature difference, and entransy dissipation rate of the body can be calculated by the measured results, respectively. Experimental results are compared to those obtained by numerical calculations; the results show that for the + shaped high conductivity channels in a square body, the maximum temperatures are located between the two branches of the + shaped high conductivity channels for both experimental result and numerical calculation. The errors in the average temperature and entransy dissipation rate of the body based on the experimental result and numerical calculations are within the acceptable range. The two results verify their validity of the heat conduction constructal optimization. Compared the square body with H shaped high conductivity channel, the entransy dissipation rate of the body caused by heat conduction is reduced by adopting the first order + shaped high conductivity channel. Compared with the optimal constructs of the first order + shaped high conductivity channels based on the minimizations of entransy dissipation rate and maximum temperature difference, the entransy dissipation rate caused by heat conduction of the former construct is reduced by 5.98%, but the maximum temperature difference is increased by 3.57%. The aim of maximum temperature difference minimization helps to improve the thermal safety of a body, while that of the entransy dissipation rate helps to improve the global heat conduction performance of a body. When the thermal safety is permitted, the optimal construct based on entransy dissipation rate minimization can be adopted in the design of practical electronic device to improve its global heat conduction performance.