In order to reduce the effect of electric defrosting heat on the cold storage temperature change during defrosting process, a heat insulation defrosting device with a return air cover and outlet baffle was designed, through the different condition of experiments, then the questions that how the return air cover and partition device to influence the temperature field around the air-cooler, the cold storage temperature and the consumption of electric heating defrosting were studied through comparing the experimental data whether the return air cover and partition device was used or not. The results indicate that after using the return air cover and partition device, the temperature distribution inside the cooling fan coil is more uniform, the fluctuating temperature field outside the fan is decreased 3.2 ℃. meanwhile, the defrosting time with the device is shortened by nearly 360 s and reduce energy consumption around 9.54%, which proves that the return air cover and partition device can stabilize the storage temperature and shorten the defrosting time and energy consumption saving in the defrosting process.