A nasogastric tube structure is disclosed which comprises a first tube, a clamping member and a positioning member. The first tube has a front necking opening, a rear opening, a stopper ring on a wall thereof adjacent to the rear opening and an engaging groove on the wall thereof adjacent to the stopper ring. The clamping member comprises two corresponding positioning segments and a C-shaped clip portion for connecting the two positioning segments and engaging with the engaging groove. The positioning member is sleeved on the two positioning segments.
