A porous polymer having a pore volume of 0.3-2.5 cm3/g, the porous polymer comprising pores having a first pore diameter and pores having a second pore diameter, wherein the pore volume ratio of the pores having the first pore diameter to the pores having the second pore diameter is 1-10:1. The porous polymer is obtained by means of self-polymerization or copolymerization of at least one phosphorus ligand, and the phosphorus content of the porous polymer is 1-5 mmol/g. A porous polymer-nickel catalyst prepared from the porous polymer has significantly improved water resistance, can reduce the consumption of phosphorus ligands, omits the steps of water removal of raw materials and water control of a reaction system, and greatly saves on process equipment investment. In addition, when used for preparing adiponitrile by using butadiene, the catalyst has a high catalytic activity, a high reaction selectivity and high linearity, and is easy to recycle and reuse.