The invention discloses an electronic cigarette, an atomizing core, an atomizer and a method of controlling the electronic cigarette. The electronic cigarette comprises a battery assembly, an atomizer comprising an atomizer body and an atomizing core mounted on the atomizer body, and a main control circuit; the main control circuit comprises a sense unit for sensing remaining life cycle of the atomizing core, a compare unit for comparing data sensed by the sense unit with a preset threshold value, and a control unit for controlling on and off of the electronic cigarette depending on comparison results. Through the invention, the user can use the atomizing core in any atomizer having electrical interfaces, and close output at an optimal time of taste of the atomizing core and before producing harmful substance.