Aimed at the technical difficulties of gob-side entry retaining in fully-mechanized coalface with top-coal caving (GERFCTC), a new technique of entry-in packing is put forward. In this technique, there are three key aspects: (1) to set up the reasonable mechanic model of surrounding-rock structure; (2) to maintain the integrity of the top coal for the entry with large-section in the coal seam; (3) to control the stability of the packing body with large bulk and long distance. In order to use the new technique in the entry, which has been excavated with normal section for several years, supported by ladder-shaped steel rigid support, actual steps are put forward. The results of industrial test and field measurement show that the technique is used successfully. It can be applied in similar conditions of fully-mechanized coalface with top-coal caving (FCTC).