The imperfection of the intestinal friction model is one of the biggest obstacle of the capsule robot's development. This paper seeks to study the intestinal frictional resistance in the starting process of the capsule robot. Experiments are conducted to measure actual frictional resistance, which is found to have something to do with the velocity, acceleration and original state of the capsule robot. The analytical expression of the frictional resistance can fit the experimental result with R-square equaling 0.9605. The achievement of the article is hoped to smooth the motion and save the energy in the capsule robot's starting process.