The HL-2A NBI design parameters are hydrogen beam energy 60 keY, the pulse duration of 2 s, consist of two beam lines and injected along tangential direction. The neutral beam power will arrive 4 MW in the future. The first step is one beam line and two ion sources. The vacuum vessel consists of major chamber, minor chamber and ion source chamber and drift duct. We need a vacuum system, which capacity is sufficient and the relatively low costs of it.