Abstract: With pressure measurement experiments in wind tunnel, wind pressure distribution on the flat roof of a building in two kinds of uniform terrains and one kind of heterogeneous terrain was investigated. The results demonstrate: the mean and fluctuating wind pressure coefficients on the roof in a uniform rough terrain are larger than those in a uniform smooth terrain, and this difference of the fluctuating pressure is more significant; When the pressure coefficients are normalized by the dynamic wind pressure of the building location, fluctuating wind pressure coefficients decrease significantly and mean pressure coefficients change slowly with an increase of the distance from the terrain change point to the building location in a rough to smooth heterogeneous terrain; When the pressure coefficients are normalized by the dynamic wind pressure of upstream terrain, mean pressure coefficients at the separation area change slowly, the amplitudes at the downstream roof area increase, and fluctuating wind pressure coefficients decrease slightly with an increase of the distance from the terrain change point to the building location, but these changes are small in the range of transition boundary layer; The main factor affecting total mean wind loads on the roof is the incoming dynamic pressure.