The present paper investigates the e ect of train speed and ground clearance on aerodynamic forces of a simpli ed high-speed train. For this purpose, 20 di erent cases including trains with ve di erent speeds and four varied ground clearances were numerically simulated. The results showed that increasing the train speed had a dual e ect on increasing the vertical upward lift forces. Non-dimensional ground clearances above than 0.22 at speeds above 250 km/h resulted in dramatic upward lift forces and led to train instability. At ground clearances below than 0.092, a rise in the speed increased the downward force, enhancing the stability of the train. Moreover, further analysis of the ground clearance e ect demonstrated that at a ground clearance equal to about 0.048, the lift force remained approximately constant at di erent train speeds. The air velocity pro les for the train experienced a dimensionless rise with increase in the value of ground clearance, except for the front part of the train. This increase was precisely apparent at a speed of 350 km/h and resulted in a 29% increase in the air velocity along the sections below the train. This rise in speed may disrupt the balance of passengers and pedestrians as well as workers around the train.