Abstract: In order to increase the slurry concentration of low rank coal, the coal water slurry for gasification was prepared using low rank coal in Xinjiang as raw material. The slurry experiments were carried out by means of traditional process and gap-graded process, on this basis, the pilot-scale experiment was carried out. The results showed that the highest coal water slurry concentration of the coal was 51.01% under the traditional process. Under the condition of the mass ratio of coarse to fine was 6:4, the highest coal water slurry concentration was up to 57.08% adopting gap-graded process, we found that the slurry concentration 6% higher than the traditional process. While by using pilot-scale experiment, the highest coal water slurry concentration is 56.19%, which was 5% higher than the traditional process, but slightly lower than the gap-graded process in the laboratory. The results of pilot-scale experiment effectively verified the results of the laboratory's small-scale test, and the pilot-scale equipment can run stably for a long time.