Head　up　displays　(HUD)　is　an　emerging　way　and　hot　topic　of　in-vehicle　human-computer　interaction　in　connected　environment.　The　human　factor　testing　of　automotive　HUD　is　a　fundamental　step　to　ensure　the　expected　safety　benefits.　This　paper　introduces　the　classification,　the　application　status,　and　the　suggested　information　of　HUD;　The　knowledge　maps　of　human　factors　research　of　HUD　are　drawn　to　clarify　the　key　content　of　previous　research　and　its　changing　trend　with　time　and　space;　And　the　paper　puts　forward　the　general　testing　framework　of　HUD　from　the　functional　scenarios,　test　variables,　and　test　methods;　and　further　discusses　the　human　factors　testing　in　the　scenarios　of　navigation,　safety　assistance,　automated　driving,　and　other　interactive　assistance　tasks.　Finally,　it　summarizes　the　existing　research　gaps　and　put　forward　the　future　research　prospects　for　human　factors　research　of　HUD,　and　provides　references　for　the　construction　of　the　intelligent　cockpit　in　connected　environment.　©　2022　Journal　of　Automotive　Safety　and　Energy.　All　rights　reserved.