The application of the isozyme technique for study in discrimination of tulip-tree hybrids was discussed in this paper. The results obtained from isozyme analysis pointed out that the patterns of gel electrophoresis of two parental trees were quite different from each other, both of the parental zymograms were reappeared in the gels of hybrid progenies with some additional hybrid bands. It is evident that the genetic bases of the two parental trees are complemental and the heterosis of progenks of Liriodendron chinescs X L. tulipifera are relatively strong. This was also proved by field test.