An electronic cigarette with a vaporizer having dual cavities and dual air passages comprises a vaporizer and a battery rod which are detachably connected, wherein the vaporizer comprises a housing and a vaporizing device. A partitioning portion divides the inner cavity of the housing into a large cavity and a small cavity. A first air outlet pipe provided in the small cavity, an air outlet through-hole provided in the vaporizing device and a second air outlet pipe provided in the battery rod are connected in sequence to form a suction sensing air passage. The air intake hole, the air inlet passage, the air inlet cavity, vaporizing chamber, the vapor tube and the vapor outlet hole which are arranged in the housing are connected in sequence to form a smoking air passage.