An inkjet printing device is provided. The second liquid storage tank is connected to a second buffer tank and the second buffer tank is pressurized so that the pressure at one side of the spray head near the second liquid storage tank is greater than the pressure at another side near the first liquid storage tank. As a result, the chemical solution in the spray head flows back into the first liquid storage tank or the liquid supply tank. Consequently, there is no residual chemical solution at the spray head so that the problem of the blocked spray head is not induced. Furthermore, by pressurizing the second buffer tank, the boiling point of the chemical solution can be reduced. The volatilization and solidification of the chemical solvent is reduced even further. Therefore, the problem of the blocked spray head is further mitigated. The quality of the chemical solution is ensured for a long time.