The invention provides a nitrogen and phosphorus nutrition slow release agent, a preparation method and application to repair of petroleum pollution intertidal zones. The nitrogen and phosphorus nutrition slow release agent comprises struvite and isobutylidene diurea. The nitrogen and phosphorus nutrition slow release agent is simple in preparation, cheap and easy-obtained in raw material, free ofsecondary pollution, easy to carry out and used for overflow pollution repair of the intertidal zones, can effectively resist the seawater dashing dilution in the petroleum pollution intertidal zonebiological repair process, and can continuously urge the growth supersession of petroleum degradation microorganisms under the condition of not influencing the intertidal zone landscape; and under anirritation effect, the removal rate of intertidal zone origin microorganisms to the petroleum pollution within 104 days is 39.42%, and is prominently higher than 22.38% in natural attenuation.