Abstract: In public buildings, ventilation and air conditioning installation engineering is a system engineering with high complexity, which involves the air volume construction of air conditioner, water system construction, infrastructure construction, insulation layer construction and other links, and faces many difficulties in engineering installation, which puts forward higher requirements for installation technology and construction organization. In order to ensure the installation quality of ventilation and air conditioning engineering in public buildings, combined with specifi c engineering cases, this paper combs the technical diffi culties in the installation of ventilation and air conditioning engineering in public buildings, and puts forward effective strategies to solve the relevant diffi culties, so as to provide certain reference for relevant installation units and installation personnel.