The invention relates to an ultraviolet intensity monitoring method and a system, and a mobile terminal. The ultraviolet intensity monitoring method is applied to the ultraviolet intensity monitoring system and to a mobile terminal equipped with the ultraviolet intensity monitoring system, and is used to monitor the ultraviolet intensity of the place where the mobile terminal is located. The ultraviolet intensity monitoring method includes the following steps: acquiring the intensity ratio of visible light to ultraviolet in the local solar spectrum; detecting the local visible light intensity; and calculating the local ultraviolet intensity according to the local visible light intensity and the intensity ratio of visible light to ultraviolet. According to the ultraviolet intensity monitoring system and the ultraviolet intensity monitoring method, the local ultraviolet intensity is calculated through acquiring the local visible light intensity, and according to the intensity ratio of visible light to ultraviolet. Therefore, accurate local ultraviolet intensity data can be provided for users, and users are enabled to take protective measures according to the actual ultraviolet intensity.