The Cosmic-Ray Energetics And Mass (CREAM) instrument for the International Space Station (ISS) is a detector for studying the origin, acceleration and propagation mechanism of high-energy cosmic rays. The ISS-CREAM instrument is scheduled to launch in 2017 to the ISS. The Top and Bottom Counting Detectors (TCD/BCD) are designed for studying electron and gamma-ray physics. The TCD/BCD are composed of a plastic scintillator and an array of photodiodes The active detection areas of the TCD/BCD are 500 $\times$ 500 mm$^2$ and 600 $\times$ 600 mm$^2$, respectively. The TCD/BCD were completed in 2015 and passed the environmental tests for safety in a space environment. After finishing these tests, the TCD/BCD were integrated with the payload. The TCD is located between the carbon target of the ISS-CREAM instrument and the calorimeter, and the BCD is located below the calorimeter. The TCD/BCD can distinguish between electrons and protons by using the different shapes between electromagnetic and hadronic showers in the high-energy region. We study the TCD/BCD performance in various energy ranges by using GEANT3 simulation data. Here, we present the status of the electron and proton separation study with the TCD/BCD simulation.