After analysis of reproduction records of two types of karyotypes (2n=50 & 2n=49) of triple crossbreed buffaloes (TCB) and studies of synaptinemal complex and sperm chromosome of 2n=49 TCB, the results showed that 2 sorts of normal gametes (n=24 and n=25) and 2 sorts of abnormal gametes (n=24+1 and n=25-1) were produced in 2n=49 TCB. Thus, both male and female of 2n=49 TCB are reproducible, and chromosomal polymorphyism (2n=50, 2n=49 & 2n=48) occurred in the progenies after intermating. But its fertility decreased because of aneuploidy combined between normal and abnormal gametes. Compared with 2n=50 TCB, the conception rates for individual inseminations and for whole year reduced 12.3% and 6.4%, calving interval were prolonged by 97.6 days, and calf numbers in its lifetime (up to 11-year old) were lower by approximate 1.5 calves, respectively.