Abstract: Double neutron stars are important objects in astrophysics and very important for many scientific studies. In 2017, LIGO/Virgo first discovered gravitational waves from the double neutron star merger GW170817, indicating a new method of discovering these stars. In this paper we shall describe the isolated binary formation scenario of double neutron stars and the properties of their populations. In addition, we discuss the binary formation channel for the GW170817 merger and some uncertainties in binary evolution, which are important for the formation of binary neutron stars.