Abstract: Three kinds of abnormal isozymic expression, paternal allele being inhibited,delay in parental gene activations and preferential gene expression of the maternal allele, occur in diploid hybrids between distant parents. Since the incompatibility between two parental alleles, and every allele only controls the half amount of product of gene, the hybrid embryos all appear "double haploid" syndrome and die in the hatching period. In the triploid distant hybrids which obtained two maternal genomes, the insufficient dosage of gene was compensated by the maternal double alleles and the disturbances of spatial and temperal expressions of paternal heterogenetic alleles are possibly inhibited by double maternal alleles. As a results, the normal metabolism and development occur and the triploid hybrid embryos can pass hatching period and grow into adults.