A conic bundle is a contraction between normal varieties of relative dimension such that the anit-canonical divisor is relatively ample. In this talk, I will prove a conjecture of Shokurov which predicts that, if is a conic bundle such that has canonical singularities, then base variety is always -lc, and the multiplicities of the fibers over codimension points are bounded from above by . Both values and are sharp. This is a joint work with Chen Jiang and Yujie Luo.