The invention discloses an environmentally friendly high elasticity sealant, which is composed of a component (A) and a component (B). The component (A) is composed of silane modified polyether, a silane coupling agent, a water remover, polyether polyol, isocyanate, a plasticizer, a filling material, and an antifoaming agent. The component (B) is prepared by mixing following components: a plasticizer, nano calcium carbonate, a curing agent, a pigment, a catalyst, a thixotropic agent, a silane coupling agent, a light stabilizer, and a UV absorbent. The component (A) and the component (B) are mixed evenly according to a ratio of 10: (0.7-1.0) before using. The prepared sealant has the characteristics of environmentally friendly property, good weatherability, low cost, wide performance adjusting range, and excellent mechanical properties, and can be well adhered on various basic materials such as glass surface, cement surface, stone, and the like.