Objective To study the relationship between the expression ratio of heat shock protein (HSP) 70 to C-fos in organs outside the brain after brain concussion and the time of injury in rats, in order to provide a new visual angle for determining injury time of brain concussion. Methods The model of brain concussion was established through free falling method. Then the rats were executed at 30 minutes, 1 hour, and 3, 6, 12, 24, 48, 96, 168, 240, 336 hours after injury. Immunohistochemistry staining of C-fos and HSP70 were used in the materials from the main organs including heart, liver, spleen, lung and kidney. All related experiment results were studied by using a microscope with image analytical system and homologous statistics. Results From 30 minutes to 6 hours after injury, the proportion of HSP70 immuno-positive cells increased slowly, while the proportion of C-fos immuno-positive cells increased rapidly, and the ratio of HSP70/C-fos positive cells was on the decline. From 6 to 12 hours after injury, the proportion of HSP70 immuno-positive cells rose continuously, while the proportion of C-fos immuno-positive cells started to decrease, and the HSP70/C-fos ratio showed a rising tendency. From 12 to 336 hours after injury, the proportion of HSP70 immuno-positive cells decreased slowly, while the proportion of C-fos immuno-positive cells decreased rapidly, and the HSP70/C-fos ratio was still on the rise. Conclusions The proportion of positive cells and ratio of the two markers in the main organs including heart, liver, spleen, lung and kidney are similar to those in the brain of rats after brain concussion. Observing the proportion of positive cells of the two markers together with their ratio in the main organs outside the brain may provide a reference for the determination of injury time after brain concussion.