From the mid of 1970s, an Italian professor named Pietro Lunardi started to study on the design and construction of tunnels using the approach based on the analysis of controlled deformation in rocks and soils (ADECORS approach in short) and gradually established a system of design and construction of tunnels by means of ADECORS approach, which in Chinese is called New Italian Tunneling Method (NITM in short). The theoretical basis of ADECORS approach, the procedures of the design and construction of tunnels by means of ADECORS approach and the differences between ADECORS approach and NATM are presented, which can provide reference for the application of ADECORS approach in China.