Full jet current ventilation has many benefits such as low construction cost, good use of traffic wind, easily implement by stages and low operating costs, which is usually applied into highway tunnel with length less than 5000m. Field tests were carried out to study the air pressure distribution of highway tunnel with full jet current ventilation. Test results show that the air pressure at the tunnel entrance is above ambient atmospheric pressure; the air pressure at the tunnel exit is below ambient atmospheric pressure and there is a point at which the air pressure is equal to the ambient atmospheric pressure. This test can provide reference to the design of full jet current ventilation.