A portable light with spectrum control means which allows the user to adjust the output spectrum manually and conveniently. The portable light includes compact housing with waterproof design and excellent heat dissipation, and it is preferably powered by batteries. A light source with multiple light-emitting units is aligned with light mixing and projecting components to produce light with uniform and consistent output synthetic spectra. Peripheral components, such as tactile switch, potentiometer, etc., and the electrical control circuit work together to respond to the user's actions to adjust the spectrum of the output light. The power management module regulates the electrical output of the power source to maintain a consistent light output as the power source drains.