The present disclosure relates to the field of energy storage materials, and particularly, to an electrolyte and an electrochemical device. The electrolyte includes an additive A and an additive B, the additive A is selected from a group consisting of multi-cyano six-membered N-heterocyclic compounds represented by Formula I-1, Formula I-2 and Formula I-3, and combinations thereof, and the additive B is at least one unsaturated bond-containing cyclic carbonate compound. The electrochemical device includes the above electrolyte. The electrolyte of the present disclosure can effectively passivate surface activity of the positive electrode material, inhibit oxidation of the electrolyte, and effectively reduce gas production of the battery, while an anode SEI film can be formed to avoid a contact between the anode and the electrode and thus to effectively reduce side reactions.