The invention provides an external sorbent floating head type adsorbent bed refrigeration unit. The refrigeration unit comprises an adsorbent bed, an insulation connective closed body, a condenser, an adiathermance connective closed body and an evaporator, wherein the adsorbent bed comprises a closed shell and a metal tube; the metal tube is arranged outside the closed shell; two ends of the metal tube extend out of the upper end of the closed shell; the sorbent is solidified on the outer wall of the metal tube; a mass transfer channel is arranged between metal tubes; the condenser is formed by outer fin tubes; the evaporator is formed by outer fin tubes; the lower end of the closed shell of the adsorbent bed is communicated with the upper end of the insulation connective closed body; thelower end of the insulation connective closed body is communicated with the outer fin tubes of the condenser; the lower ends of the outer fin tubes of the condenser are communicated with the upper end of the adiathermance connective closed body; the lower end of the adiathermance connective closed body is communicated with upper ends of the outer fin tubes of the evaporator; and the lower ends ofthe outer fin tubes of the evaporator are closed. The adsorbent refrigeration unit has scientific structure design, strong capability of adapting to reversed heat stress, does not leak in operation, and has prominent adsorbent refrigeration effect.