In order to solve the problem of low utilization of zinc micro-fertilizer being applied directly into soil，the adsorption characteristics and repeated slow-release properties of zinc with different particle sizes of Water Absorbent Polymer(WAP) were studied.The Langmuir and Freundlich isothermal adsorption equations were used to fit and analyze the experimental adsorption data of the four particle sizes of WAP(M，L，L1 and L2)，and the results showed that they were suitable for the Freundlich isotherm adsorption model，which was multi-molecular adsorption，and the adsorption difficulty was moderate.The adsorption of Zn2+ by WAP was fitted by the Pseudo-second-order model(R2 >0.99)，which was mainly chemical adsorption.The adsorption equilibrium time was 60 min(M)<240 min(L)<1320 min(L2)<1360 min(L1)，the order of equilibrium adsorption was L1>L2>L>M，that is，L1(4～6 mm) particle size had the longest equilibrium time and the highest zinc adsorption capacity.The cumulative zinc release of the WAP is expressed as L1，L2>M，L，larger-diameter water-retaining agent L1(4～6 mm)and L2(6～10 mm)released more zinc ions under the same conditions and had better fertilizer release effect.FT-IR analysis showed that the ion exchange and complexation of the functional groups in the WAP played an important role in the adsorption and fixation of Zn2+.Taken together，among the four kinds of WAP with different particle sizes tested in this article，the WAP with a particle size of 4 to 6 mm(L1)has the best performance from the perspective of absorption and release of fertilizers in different concentrations of solutions.It is recommended as a zinc fertilizer slow-release carrier to avoid the problem of low bioavailability of zinc in the soil caused by the direct application and low fertilizer utilization.