The invention discloses a phosphorus nitride adsorbent with high-efficiency selectivity, and its application thereof. The phosphorus nitride adsorbent has a mutually cross-linked hollow tubular structure. The adsorbent can have an adsorption capacity of 435.58 mg·g−1 and 7.01 mg·g·1 for spiked seawater and natural seawater with a uranium concentration of 350 ppb, and the adsorbent has a long service life, and can still maintain 91.14% of the initial adsorption capacity after 5 cycles of adsorption and desorption. Taking into account the advantages of a short material preparation cycle, a wide range of raw material sources, a low cost, an excellent adsorption performance, and long service life, the adsorbent can be used in technical fields such as uranium-containing wastewater treatment, uranium ore resource recovery, uranium extraction from seawater and the like.