  The existing life table method needs to calculate the age-specific mortality
first, not only has too many and complicated calculation steps, but also
introduces the multiple approximation to bring error. This paper redefines the
probability of death for the life table as the average probability of death of
a group of people born in a certain period at a later time. Based on this
definition, a new method for the life table is proposed to obtain the life
expectancy, which has the same meaning to that from the traditional life table.
Using the Japanese population data to verify the method, the results show that
it is consistent with the life expectancy of the birth of the baby, the maximum
relative difference is no more than 0.1%, and average relative difference is
less than 0.03%. The theory and method of life table described in this paper
are simple and easy to understand. The needed data are easy to obtained from
statistics, and the calculation is easy, the results obtained are accurate and
reliable. It should be a very valuable demographic method for application.
