Because of their ability of self-clean, superhydrophobic surfaces have received substantial attention for years especially in surface science field. In this paper, the drop's wettability on different rough surfaces is simulated by using many-body dissipative particle dynamics (MDPD) and a contrast with the Cassie-Baxter theory's predictions is made. A combination of short-range repulsive and long-range attractive forces is used as wall-fluid interaction to generate different wettability, and a simple but efficient numerical method is introduced to measure the contact angle. The simulation could capture the static and dynamic properties of drop on textured surfaces, it is also shown that the microstructured surfaces can pin the three-phase (solid-liquid-vapour) contact line and this phenomenon has also been observed by other researchers in their physical experiments, suggesting that people should be careful when using the Cassie-Baxter theory. An analysis was given about energy transformation between kinetic energy and surface energy. The simulated results also show that the low Φs can cause the drop to rebound easily under the same impact velocity.