Cryptand resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of $1\%,;2\%,;5\%;and;10\%$ by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium$(UO_2^{2+})$ ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium$(UO_2^{2+})$ > zinc$(Zn^{2+})$ > samarium$(Sm^{3+})$ ion. The adsorption was in order of $1\%>2\%>5\%>10\%$ crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.