The invention discloses an epoxy resin flame retardance curing agent containing phosphorus and nitrogen and a preparation method of the epoxy resin flame retardance curing agent, and relates to a chemical curing agent and a preparation method thereof. Preparation raw materials comprise phosphorus oxychloride, 1-oxy-phospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane, and m-xylylenediamine. The preparation method comprises the following two steps: firstly, ensuring that phosphorus oxychloride (POCl3) and 1-oxy-phospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (PEPA)react with each other in a certain condition, so as to generate phosphorus containing intermediate; secondly, ensuring that the intermediate obtained in the first step and m-xylylenediamine are stirred and react with each other for a certain time with the leading of inert gas, and carrying out filtering, washing and drying to obtain white solid. The curing agent has good compatibility with epoxy resin, can be cured into a whole body with epoxy resin, and is small in influence on the mechanical property of a cured material, can not only serve as a curing agent for epoxy resin, but also effectively improve the flame retardation of epoxy resin.