Univ Sci & Technol Beijing, Dept Phys, Beijing 100083, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Peking Univ, Dept Phys, Beijing 100871, Peoples R China
Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronic gas model for nuclear matter. The relative yield ratio of tetraquark cs (s) over bar(s) over bar to Omega is less than 0.0164.