The present paper presents the design of a vacuum compatible automatic targets feeding system (VCATFS) that can be used to introduce targets inside the interaction chambers for accelerators, laser beams and others research plants. As a first application, the system is to be used within the Extreme Light Infrastructure -Nuclear Physics (ELI-NP) project, to load target frames in the interaction chamber without losing the vacuum. The target frames will be inserted and retracted into/from the interaction chamber individually with high accuracy of positioning. Up to three target frames can be used during one experiment. This number of targets is a consequence of several severe spatial constraints where the system will be installed, but for other situations it can be increased. Also, a new technique of moving the target frames is proposed, two horizontal translations in two parallel planes and two vertical translations also in two parallel planes. VCATFS is divided into two main sub-systems: mechanical (includes kinematics, high precision components and systems, vacuum chamber), and a dedicated command and control system (transducers -high accuracy absolute linear encoders, stepper motors and associated electric drives unit, interfaces and proprietary software). Additionally, a dedicated vacuum system was designed. This approach will further be developed as prototype level. This paper will focus on the design of mechanical sub-system, the remaining ones will be the subject of future documents that would be made publicly available in the future.