The invention discloses a phthalonitrile monomer containing aromatic polyamide, which is characterized in that a structural formula of the monomer is shown in the description, wherein R1, R2 and R3 are groups shown in the description or H atoms, which can be identical or can be different, and at least one substituent group of the R1, R2 and R3 contains an amide group, and a carbonyl C=0 characteristic peak displayed through an infrared spectrogram of the monomer is between 1650 and 1660. The invention also discloses a preparation method of the monomer and prepared poly phthalonitrile resin by using the monomer. The phthalonitrile is a monomer having an autoacceleration thermal polymerization behavior, during solidification of the phthalonitrile, no arylamine or phenolic curing agent is required to be added, the cost is saved, the operation is simplified, the quality can be controlled easily, besides, defects of a traditional phthalonitrile resin two-component system that the blending process is complex, the energy consumption is high and the like are avoided, and industrial production is facilitated. The method is simple, mature, easy to operate and control, and convenient for application.