The present invention discloses a urinal with a conductivity sensor, which includes the conductivity sensor arranged at the location where a reservoir of the urinal is curved and adapted to detect urine, a control unit (MCU), a power battery, and an electromagnetic valve adapted to control a discharge of water, wherein the conductivity sensor is adapted to detect a conductivity to determine whether urine is present. After the conductivity sensor detects presence of urine, the control unit opens the electromagnetic valve. The conductivity sensor includes electrodes dipped inside the location where the reservoir is curved to contact urine. The conductivity sensor further includes an anti-polarization-of-electrode circuit based upon the principle of an alternating power supply. Thus, the sensor can achieve more reliable sensing and a longer lifetime.