To study the wind speed-up effect of real terrain， the geometric features of real terrain were extracted to establish an ideal simplified terrain. Then， the π-shaped mountain range was proposed in this paper. The CFD numerical simulation was used to study the influence of the distance， length， and slope of subsidiary mountain ranges on the wind speed-up effect at the main ridge line in the wind direction along subsidiary mountain ranges. The difference in the speed-up ratio of the main ridge line between the π-shaped mountain range and the three-dimensional cosine-shaped mountain range was compared by combining with the terrain characteristics. Based on the latter， a simplified calculation formula of the wind speed-up ratio at the feature points of the main ridge line of the π-shaped mountain range was obtained and verified by a true π-shaped mountain range. The results showed that the speed-up ratio at the midpoint of the main ridge line of the π-shaped mountain range was greatly affected by the distance and the length of the subsidiary mountain ranges， and the speed-up ratio at the intersection point of the ridge line was greatly affected by the length and slope of the subsidiary mountain ranges. Compared with the three-dimensional cosine-shaped mountain range， the speed-up ratio of the main ridge line of the π-shaped mountain range was the same at the end of the ridge line， but it was smaller as a whole， especially the part shielded by the subsidiary mountain ranges was significantly smaller. The difference disappeared after exceeding the height of 70m above the ground. Compared with the wind field of the real π-shaped mountain， it was found that the simplified terrain and simplified calculation formula can reflect the speed-up effect of the feature points at the main ridge line of the real terrain.