More trouble for Aldon Smith ... the ex-NFL star was arrested (again) for allegedly driving under the influence.
Smith -- a former All-Pro linebacker -- was arrested early Tuesday morning on suspicion of DUI in Mission, Kansas ... after cops say he was speeding and illegally changing lanes.
Officials says they suspected Smith was drunk, and tried to administer a breathalyzer ... but he refused, so police issued him a citation for DUI.
Luckily for Aldon, cops didn't haul him off to jail ... they let a friend pick him up from the scene.