Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Inst Phys Nucl, IN2P3, CNRS, F-91406 Orsay, France
; Univ Paris Sud, F-91406 Orsay, France
Within the extended Ginzburg-Landau model, multiplicity difference correlators in first-order quark-gluon plasma phase transition are investigated for two well-separated bins with nonidentical mean multiplicities. For very small bin width, a kind of scaling behavior and a universal exponent index gamma, which are independent of the parameters of model, are found.