We report a caesarean operation to cleaning C57BL/6 mice in half-barrier system .The parturient term of pregnant mice was measured by method of palpation and method of calculation, and the survival rate of birth mice ware 89.52% and 91.75%,respectively had no diffevence.But we think in practical application,palpation may be useful in the measurement of clean caesarean mouse parturient term in half-barrier system.