The invention provides benzoxazine resin containing propargyl and a preparation method of the resin. The benzoxazine resin has a molecular structural formula shown in the description. According to detection, the benzoxazine resin prepared with the method has better insulation performance and lower dielectric loss, propargyl contains nitrogen elements, the nitrogen content of a benzoxazine cured material can be increased, so that the flame retardance of the resin system is improved, the electrical insulation property is excellent, industrial production is convenient, the yield is high and the benzoxazine resin has high industrial value and actual application value. The preparation method of the benzoxazine resin containing propargyl adopts a two-step method, an intermediate is prepared in the first step, the intermediate is chemically modified in the second step, and the preparation process is simple, environmentally friendly and low in cost.