Abstract: Starting from the equations describing typhoons in the atmosphere the steady three-dimensional stream field and the corresponding pressure and temperature fields are obtained. The three-dimensional velocity fields construct a nonlinear autonomous system in the physical space. It is shown that the centre of typhoon is a local minimum pressure with positive vertical vorticity (cyclonic vorticity) and horizontal convergence in lower levels and a local maximum pressure with negative vertical vorticity (anticy-clonic vorticity) and horizontal divergence in upper levels. Because there exist two saddle-focus points in the autonomous system so there exist the spiral patterns in which the winds blow spirally inside and outside the centre in lower and upper loveis in the Northern Hemisphere and cause the ascending motion near the the rotation of the earth and viscosity of air play an centre. These are in conform fairly well with the observations. It implies that important role in the spiral structure of typhoons.