Monolayers with high viscosity compressed in the conventional Langmuir trough are not uniform. In this paper, a new method for uniform compressing of Langmuir monolayer is reported. The compressing system consists of an array of Teflon cones, which have holes at the bottom. By lifting the cone array from the water into the air, the Langmuir monolayer at the air-water interface can be separated into small pieces and every piece of the monolayer can be compressed by the Teflon cone. The distribution of the surface pressure of aluminum stearate monolayer is studied by using the cone system. The advantage and disadvantage of the new compressing system are compared with other troughs.