It was conjectured by Painleve in 1897 that there exists noncollision singularities (NCS) in Newtonian N-body problem for N>3. NCS is a kind of initial conditions leading to solutions blowing up to infinity in finite time. Xia proved the conjecture by showing the existence of NCS in a five-body problem. It remained open if NCS exists in four-body problem or not. We will explain our work on the existence of NCS of four-body problem in two different models.