The Dalian coherent light source is a free-electron laser facility based on the principle of high-gain harmonic generation, which can generate lasers with full coherence, short pulse and high peak power in 50~150nm. Advanced laser tools can be provided for exploring molecular ionization and dissociation in nature. The main function of the beamline for Dalian coherent light source is to transmit the laser efficiently to the end experimental station and perform optical diagnosis such as light intensity and spectrum. Dalian coherent light source beam line consists of Beam Define Aperture (BDA), gas monitor detector (GMD), Beam Position Monitor (BPM), Photon Block (PB), gas absorber (GA), profile monitor (PRF),on-line spectrum and several different functional mirrors including a focusing mirror and three deflecting mirrors. In this paper, the basic principles and mechanical structure of each functional module are briefly described.