Abstract: The radius of Mars is only half of that of Earth, while the height of Mount Olympus, the highest mountain on Mars, is more than twice of that of Everest on Earth. There are still some peaks on Mars which are much higher than Everest. To explain the appearance of mountains or protrusions disproportional to the scale of the planet, a stress model of a mountain was set up. It was found that the main factor that affects the highest mountains height is gravitational acceleration. The smaller the planet, the smaller its surface gravitational acceleration, and the more prominent the protrusions on its surface. The depth of the deepest trench on Earth was also estimated using the same method; the result is close to reality.

Key words: Mars, Earth, peak, the greatest height