The curcian carp (Carassius auratus gibelio Bloch) is distributed mainly over Europe， northeast and northwest China．In northeast China，especially in Heilongjiang water， the crucian carp has two subspecies．The one was considered to be troploid that has 150± chromosomes in its somatic cells， and reproduces by gynogenesis． There are only some 5%-25% males in this population． The other was regarded as diploid whose somatic cells has 100± chromosomes． Spermary histological structures of triploid and diploid in crucian carp (Carassius auratus gibelio Bloch) were investigated by means of light microscope．The results indicated no abnormalities were found in spermatogenesis of the triploid，and its spermary which is similar to the diploid is lobular type which constituted by out membrane and parenchyma． The seminiferous lobulas are composed of several cysts and distribute in radiation．The spermatocyte and immature spermatid located in the permatogenic cysts，after spermatozoa have matured， the spermatozoa were released into lumen of seminiferous lobula out of the spermatogenic cysts． There were several leydig cells among seminiferous lobulas． However，mature spermatozoa in lobule lumen o f the triploid were obviously less than those in the diploid．The crucian carp m ay have reproduced gynogeneticaly before diploidization but has now become diplo id in behaviour．The change of reproductive form might be a long transition peri od． The triploid is fertile and can form mature spermatozoa after meiosis，whic h was regarded as triploid would be hexaploid or is undergoing the course of dip loidization．