  In this paper, we estimate the proportion of zeros of Dirichlet $L$-functions
on the critical line. Using Feng's mollifier and an asymptotic formula for the
mean square of Dirichlet $L$-functions, we prove that averaged over primitive
characters and conductors, at least 61.07 % of zeros of Dirichlet $L$-functions
are on the critical line, and at least 60.44 % of zeros are simple and on the
critical line. These results improve the work of Conrey, Iwaniec and
Soundararajan.
