The invention discloses a method for removing 1,1-difluoro-2-chloroethylene in 1,1,1,2-tetrafluoroethane by adsorption. The method comprises the following steps: a 1,1,1,2-tetrafluoroethane crude product containing 1,1-difluoro-2-chloroethylene is in contact with a Cu(I) ion exchange modified molecular sieve adsorbent under a gas phase condition; and chemical adsorption is carried out on the 1,1-difluoro-2-chloroethylene by the adsorbent, so that the 1,1-difluoro-2-chloroethylene is removed from the 1,1,1,2-tetrafluoroethane crude product, and a purified 1,1,1,2-tetrafluoroethane product is obtained. Through adoption of the technology, the 1,1-difluoro-2-chloroethylene in the 1,1,1,2-tetrafluoroethane is high selectively removed at a lower adsorption temperature according to the characteristic that pi-complexation adsorption belongs to chemical adsorption, the adsorption capacity is large, the adsorption speed is high, and the method is environmentally friendly. The regeneration temperature of the adsorbent is not high, the regeneration performance of the adsorbent is excellent, requirements of large-scale industrial production can be met, and a good industrial application prospectis achieved.