Objective To discuss the methods to accurately define the time of confinement in rats in order to make ceasarean section at the appropriate time and to obtain healthy newborn rats. Methods To compare and analyze the accuracy of judgment methods on rat confinement date, including computation, palpation, observation, integration and remediation. Results The accuracy of computation method was 85 %. The accuracy by use of palpation, observation, and integration methods was 73 %, 69 %, and 87 %, respectively. Remediation method may somewhat delay the time of gestation. Conclusions It is of great value to improve the confirmation of the pregnant rat gestation and accuracy of the date of production by palpation and observation combined with computation method.